When you're 16, every Monday is the worst day of your life. 14 March 2005 was a Monday and so Mats Hummels was sitting morosely in a Munich classroom facing another endless school week and too many days until the next game. He looked outside the window into a cold and windy day and his thoughts wandered for a while, until they ended up revolving, as usual, around Reutlingen. His Bayern Munich Under-17 team wouldn't be playing SSV Reutlingen on the coming weekend, but that didn't matter. Young Mats Hummels often thought about Reutlingen, because for some reason they always gave Bayern a lot of trouble.

Mats was dimly aware that while he was worrying about South German youth football rivals, Borussia Dortmund were having more serious problems. He had read that the club was in financial difficulties, but it didn't unduly bother him. First, he hadn't much to do with Dortmund. Second, many football clubs had run up huge debts, but it didn't seem to make any difference. Take Real Madrid. They were many hundreds of millions in the red, right? And nobody gave a hoot, right?

While Hummels thought some more about Reutlingen and cursed school, the 38-year-old Jürgen Klopp was preparing for an eventful week some 400km to the north-west. Klopp was coaching FSV Mainz 05, a club that was only two days away from its 100th birthday, an event that would be celebrated with a ceremony on the Wednesday in the State Theatre. 

For the time being, however, Klopp was more occupied with his team's game at Werder Bremen two days ago. After the final whistle, he had run onto the pitch to wrap his arms around his goalkeeper, who had secured a scoreless draw and thus a valuable point for Mainz in the relegation fight. Then the team had driven seven hours through a snow storm to get back home. Klopp also wasn't giving much thought to Borussia Dortmund. He had heard something was amiss there, but he didn't know the details and, like Hummels, he felt the situation couldn't be that serious, let alone dramatic. As far as Klopp was concerned, Dortmund were a big club, maybe even a very big club, that appeared to have made some decisions that hadn't been ideal. These things happen.

While Klopp was concerned with football games and a birthday party, a man in his early thirties by the name of Jens Volke was beginning to wonder what would happen if a situation that was already serious did become dramatic. Volke was standing in the Düsseldorf airport compound, a two-hour drive north-west of Mainz, and staring at a cheap, ugly building made of corrugated steel.

Inside this building, 444 people from all over the country who had never seen each other before were sitting on plastic chairs, listening sceptically to what representatives of Borussia Dortmund were trying to explain to them. Outside, in the cold, Volke and not more than nine or ten other people were shivering and becoming increasingly nervous the longer the morning dragged on. The club had asked its fans to stay away from Düsseldorf so as not to put pressure on those 444 men and women. (You never know how people react under pressure, right?) But Volke couldn't help it. He had to be here. There was no way he would spend this Monday in an office.

Daniel Lörcher, however, didn't have much of a choice. 14 March 2005 was his very first day in a new job, and so he was sitting in the offices of an insurance company 60 miles east of Düsseldorf — in Dortmund. The 19 year old hailed from a small city near Stuttgart, where Jürgen Klopp was born, but he'd grown up as a devoted Borussia supporter. So devoted, in fact, that he'd moved to Dortmund seven days earlier to save himself the constant travelling from Swabia to the Ruhr area. 

"I'm sorry, but we can't allow you to listen to the radio or anything like that," the boss said when his new employee walked in. Daniel nodded his head.

"But I tell you what," the man went on, "I will listen to the radio. And as soon as there's any news, I'll inform you."

"That's very kind of you," the young Swabian replied. "Thank you."

"Well," his boss said, "I know how much this means to you."

For some reason he couldn't explain himself, Daniel had mentioned in his job application that he wanted to live and work in Dortmund because Borussia was his life. Now he was not only dating a beautiful Dortmund girl and living in a nice flat in the city, he had also found a job, which wasn't easy in a region that had western Germany's highest unemployment rate. Yet young Daniel Lörcher wasn't entirely happy. After all, it was quite possible that this Monday would turn out to be the worst day of his life.

Six years and one month after that fateful morning, Daniel Lörcher is standing outside a Dortmund pub, just a 10-minute walk from the football ground. It is a warm and sunny Sunday and Borussia will play SC Freiburg in three hours' time. Daniel should be nervous for two reasons. For one, this game could be crucial in the title race. Dortmund, the league leaders, are five points ahead of Leverkusen. That may look like a comfortable lead, the more so since Leverkusen will be playing away at Bayern Munich earlier in the afternoon. But Dortmund's lead was 12 points only a couple of weeks ago. It has evaporated like water in a blast furnace because Leverkusen are red-hot, having won five Bundesliga games in a row. If they win again today and Dortmund lose, the lead will be down to just two points with four games of the season remaining.

The second reason for anxiety is that Daniel is not a normal fan. He doesn't even follow the games like a normal fan. When Borussia play at home, Daniel faces not the pitch but the most famous terrace in German football, Dortmund's South Stand. For 90 minutes, he looks at a heaving mass of 25,000 people, many of whom will react to what he does. Daniel resembles a conductor, who is as responsible for a performance as the musicians and the composer. That should be enough to make you nervous. But Daniel is not nervous. He is much too busy for that.

"By the time the game kicks off," he says after finishing another telephone conversation, "my mobile's battery has usually run out." 

There are countless things to organise and check. Who carries the boxes with the 12-page fanzine that is going to be distributed at the ground? Where will the 5,000 self-printed yellow T-shirts be sold? At what time is Daniel supposed to appear on the club's own television station to talk about the campaign to keep ticket prices down? And where will he meet the two hip-hop guys who have compiled a 10-track CD with the help and the support of The Unity?

The Unity is the largest and best-known of the Dortmund ultras groups. It has 300 members, roughly two-thirds of whom are now milling about on the pavement, waiting for the go-ahead to walk up to the stadium. Ultras should not be confused with hooligans or members of regular fan clubs. They are those unusually committed supporters known for their elaborate displays, so-called choreographies, and for their continuous singing of chants that are started by one or two leaders. These leaders are the people with megaphones or microphones you sometimes see on television, the young men who are often standing on custom-made platforms, with their backs to the field of play. Men like Daniel.

A chant Daniel starts quite often these days uses the melody from the theme song to the old Pippi Longstocking television series. It asks "Wer wird Deutscher Meister?" — who's going to be German champions? — and the answer is: Borussia! "When we first sang songs about winning the Bundesliga this season, it was supposed to be funny," Daniel says with a smile. "Actually, we had a discussion about it, because some of us were afraid it would put pressure on our young team. But in the end we just went ahead and sang all those old songs that were created back in the 1990s, when most of us were kids. We did it ironically, because it would have been crazy to believe Borussia could really compete for the title." 

While Daniel is making another phone call, Jens Volke approaches him, as there are a few things the two have to discuss. Jens is not a member of The Unity, more precisely: not anymore, but an employee of Borussia Dortmund. He is the club's main fan-liaison officer. Stand next to Jens on any given weekday and you can hear him fielding calls from fan clubs or from the police, who want to know things such as how many Dortmund supporters will be travelling with the team to the next away game. Almost 20,000 are expected to make the trip to Mönchengladbach one week from now and numbers like that tend to worry policemen. But this Sunday, Jens is off duty. He doesn't have to work. But of course he still goes to the game.

"Lately I often think back to that day six years ago," he says. "Back then, we wouldn't have dreamed of what is happening now. We would have been happy with playing in the Uefa Cup again one day." He shoulders a small black backpack, because the ultras seem about to march off. "Even if all goes wrong now, we'll still be playing in the Champions League next season. And if things go well, we will win the league. This is incredible. Totally unbelievable." 

Someone a few steps ahead raises his arm and makes a gesture like a cavalry commander in an old Western. Slowly, the members of The Unity start moving towards the ground. It's officially called Signal Iduna Park, after a local insurance company. But the ultras still call it the Westfalenstadion for the same reason that none of them wears a replica shirt or any other piece of official merchandise. Something else that distinguishes these supporters from normal fans is that they vehemently oppose most aspects of the commercialisation of the game. In September last year, they even boycotted the derby away at Schalke — the derby! — as a protest against increased ticket prices.

The question whether football is the people's game or just a business rarely goes away in Dortmund, not least because Borussia is the only German club that has gone public and floated shares on the stock market. Two weeks before the Freiburg game, on April Fools' Day, some 150 people crammed into the Dortmund club museum to follow a debate among fan representatives and academics about the ultras movement. During this discussion, a Berlin author said the ultras needed to review their anti-money attitude because in a capitalist society football would always have to be a commercial endeavour. Then a former Dortmund fan spokesman reminded the ultras in attendance, who take tradition very seriously, of their club's history. "Borussia was one of the first really commercial clubs," he said. "We actually have a long tradition of commercialisation!"

Whereupon a young man sitting a few rows from the panel and wearing a plain black baseball cap without any logos muttered under his breath: "But that's the fucking point, man. Look where that got us."

Borussia Dortmund were the first German club to win a European trophy. In 1966, the team beat a strong and favoured Liverpool side at Glasgow's Hampden Park to lift the Cup-Winners' Cup. It was the biggest day in the club's history up to that point, but it also marked the end of Borussia's first golden era, a period that had lasted for about ten years. The heavily industrialised region around Dortmund, the Ruhr area, was already suffering from the decline of the coal-mining industry, when, in the late 1960s, the global steel crisis struck and destroyed tens of thousands of jobs. 

As the Ruhr's economy plummeted, the same went for the area's once-proud clubs. Essen, Dortmund and Schalke had between them won four national championships in a row between 1955 and 1958, before the formation of the Bundesliga, but now they no longer had the finances to compete. Schalke finished last in 1965 and only stayed up because the league was expanded. Essen were relegated in 1967. And in 1972, Borussia went down and would languish in the second division for four years. 

At around the same time, Dortmund was hit hard by another development: for many years, only one city in the entire world — Milwaukee — had been producing more beer than Dortmund. But one brewery after another closed down or was swallowed up by some giant corporation. It was a heavy psychological blow for the people living here, because the breweries used to be important to the city's identity. When, in 1909, 18 members of a Catholic youth organisation had formed their own football club, they used the Latin word for Prussia as their name because it was also the name of an old local brewery — Borussia.

Dortmund's dark ages, on and off the pitch, lasted for almost two decades, during which the city slowly reinvented itself as a home of insurance companies and banks, while the football club brought its finances under control and gradually rebuilt. In 1986, Gerd Niebaum, a local lawyer, was elected Borussia's president. Three years later, the team surprisingly won the German Cup and Niebaum managed to lure a smart, articulate business manager by the name of Michael Meier from Bayer Leverkusen to Borussia. Another two years later, in 1991, Niebaum and Meier signed a coach from Switzerland few Borussia supporters had ever heard of. In fact, many people presumed this new coach was Swiss. But he wasn't. Ottmar Hitzfeld was German.

These three men would lay the foundation for Borussia's second great era. Two of them would also lay the foundation for the club's downfall, but that came later. For the time being, everything went righ — even when it went wrong. In Hitzfeld's first season, the team only very narrowly missed out on a sensational league title. But the second-place finish was a blessing in disguise, because Borussia qualified for the Uefa Cup and this competition turned out to be a goldmine. Thanks to an unusual and short-lived system of distributing the German market's television money, Dortmund earned 25m Marks en route to the final. The mighty Juventus, fielding stars such as the Brazilian Julio Cesar and the Germans Andreas Möller and Jürgen Kohler, finally stopped Hitzfeld's young and inexperienced team, but the money Dortmund had made, a huge sum for the time, would be well spent.

Over the following years, Borussia signed a large number of well-known players, usually from Italy: Matthias Sammer, Karl-Heinz Riedle, then Cesar and Möller. Since Hitzfeld's biggest strength was man-management, these stars somehow got along reasonably well, played good football and had success. It earned the club more money, which was then spent on even more stars: Kohler, the Germany international Jörg Heinrich, the Portuguese Paulo Sousa. 

The system yielded a staggering amount of silverware, as the team that had been a perennial relegation candidate only a decade earlier won two Bundesliga titles, stunningly defeated their nemesis Juventus in the 1997 Champions League final and then topped it all off with the Intercontinental Cup a few months later. Borussia were, almost literally, on top of the football world. Now the trick was staying there.

Less than a year after Borussia had won the Intercontinental Cup, the German football federation (DFB) decided to make a fundamental change to its rules. Until that time, only public, non-profit organisations had been allowed to participate in league football, which meant that no German club was a privately owned business. Since the DFB is an association that is steeped deeply in the amateur tradition (in Germany, fully-professional football was illegal until the 1960s), the change was half-hearted, but it was grave nonetheless: under the new rule, clubs were allowed to turn their professional football divisions into companies and could issue shares, as long as 50 per cent plus one share would remain in the possession of the old parent club.

Most German clubs took up the option of making their teams companies, but only one club also decided to go public and float shares — Borussia. In October 2000, Dortmund sold roughly 13m shares at 11 Euros per share and earned an amazing and unexpected 140m Euros. Niebaum promised to invest that money in "Steine und Beine" — stones and legs — meaning in both infrastructure and new players. The Westfalenstadion was rebuilt until every stand had a second tier, which ultimately raised the capacity for domestic games to more than 80,000. Borussia launched its own glossy monthly magazine and also acquired or created all kinds of subsidiary companies, from a travel agency to an internet company. Finally, the club even cancelled a lucrative contract with Nike and started its own sportswear brand, called goool.de, which meant Borussia effectively supplied itself.

These measures were supposed to take care of the "stones". The "legs" belonged to men such as the Brazilian Marcio Amoroso, signed from Parma for 25m Euros, which shattered the Bundesliga transfer record, the Czechs Tomáš Rosický and Jan Koller or the Germany international Torsten Frings. Under their new coach Matthias Sammer, this team won the 2002 Bundesliga title and was very unlucky to lose the Uefa Cup final against Feyenoord in Rotterdam.

Borussia had reached that final after beating Milan 4-0 at home in the semis, with Amoroso scoring a hat-trick in the first half. It was one of the best games in the club's entire history, the atmosphere memorably electric as the thrilled fans celebrated their team, safe in the knowledge that Borussia was up there with the biggest clubs in Europe and that the future was bright.

How the beer flowed that night in pubs and homes! After all, without the coal mines and the steel mills and the breweries, football was by and large the only thing that was left to give the city an identity. Many places are referred to as football cities, but the term is rarely as fitting as it is in Dortmund, because almost everybody who was born or lives here cares deeply about Borussia and defines himself or herself to a large degree through the fortunes of the football team.

"I came to Dortmund, because football is of such central importance here," says Jürgen Klopp. "I'm not stupid, I know there are things that are more important than football. But it's what I do and what I love, so I found it very attractive that football takes centre stage here and that people live the game so intensely."

It's not an accident that "intense" is one of the words Klopp uses most often. Unshaven, as always, and dressed in a training top and football shorts, he may seem supremely relaxed on a bright, mild March morning that is almost a day off because many players have been called up to their national teams. But even when things are quiet, Klopp is intense, completely focussed on the task at hand, even though it's just a conversation. He listens intently, never misses an inaccuracy, won't let a single implication he doesn't share go by unchallenged and makes clear that he means everything he says exactly the way he says it. When he laughs, he sometimes slaps his thigh and a sound like the crack of a whip reverberates around a small, clean room in one of the two main buildings on Borussia's training area. 

"This is the most emotional football region in Germany," Klopp continues. "And even though there are some people 30 km from here, in Schalke, who will vehemently deny it, I would say Borussia is the most emotional club."

"Emotional" is another of Klopp's favourite words. And even Schalke fans cannot deny that he is the most emotional coach in the country. It would be an exaggeration to say Klopp covers as much ground as his players during a game, because very few human beings can cover that much ground, but you rarely find him standing still, let alone sitting. At the end of any given season, his protestations and frustrations, his encouragements and celebrations, will make the highlight reels on television as often as the best goals or saves.

Which goes a long way towards explaining why Borussia signed him in the summer of 2008. Klopp's contract with Mainz had run out and he was waiting for offers, ready for the next career move. Even though Mainz were in the second division at that point, having been relegated the year before, Klopp's reputation was untarnished, even excellent. Everyone knew that the young coach had somehow managed to overachieve with Mainz, a small club without money, for seven long years and many people wondered what he would be capable of at a place where the conditions were better. 

One of them was Uli Hoeness, then the business manager of Bayern Munich. He called Klopp around that time and maintains the only reason the Mainz coach didn't join Bayern was that his club's board was reluctant to have such a young and inexperienced man, driven by emotions, run the biggest club in the land. In the end, Bayern, as was their wont, settled on a marquee name on the bench, a star. "I allowed myself to be convinced we should make a stab at this Jürgen Klinsmann adventure," Hoeness told a Munich newspaper in January. "As we know now, this was a big mistake."

Borussia, meanwhile, needed exactly all those qualities that made the Munich honchos hesitate. By the summer of 2008, Dortmund had just finished 13th in the league but qualified for Europe through losing the Cup final against champions Bayern. On paper, it was not a terrible showing, but Borussia's problem wasn't necessarily the results. It was the lack of fire and enthusiasm, both on the pitch and in the stands. Most fans could remember only one really rousing game that made the hairs on the back of their necks stand up since that magic night against Milan — a derby win in 2007 that robbed Schalke of the Bundesliga title. That was sweet, yes. But at the end of the day it was memorable only because it was first-class party pooping.

"There are some regions where you have to play and live the game in a certain way," says Klopp, "where you have to charge, where you can't sit back and just knock the ball about. There are some places where, when you do that, people will say: well, if that's your football, I'd rather have no football at all. And this here is one of those places. Here, you have to give the people a certain kind of football, the kind that is close to my heart: intense to the last minute, highly emotional. Football you will remember."

Changing the football also meant changing the look of the team. Some of the players Klopp built his new side around were already there when he came, but didn't play regularly - for instance the young defender Mats Hummels, then on loan from Bayern. Hummels watched from the bench as a Dortmund team with an average age of 28.6 years lost the 2008 Cup final against Bayern. Less than three years later, when Dortmund played another important game against Bayern, Hummels would be an undisputed starter in a team with an average age of 22.2 years.

Yet it's not as if Klopp collected all those young and only little-known players because he had no choice but to buy cheap. There was some money, just not terribly much of it. "While it was clear that we would have just a certain budget because the most important thing was to consolidate the club financially," he says, "we have been able to get the players we wanted. Yes, we had to reallocate the money somewhat, but we could sign Neven Subotić from Mainz, for example, and that was the most expensive transfer — about 4.5m Euros — I'd ever been involved in. So we could do the things we considered useful. There was never a moment where I thought I would like to have more money to buy someone." 

What Klopp means by "reallocating the money" is that he allowed some high-salaried stars to leave in order to raise money that could be spent elsewhere: In his first year in Dortmund, he sold the team's best goal-scorer, the Croatian Mladen Petrić; in his second year, he sold the second-best goal-scorer, Switzerland's Alexander Frei. The money was used to make the Hummels move permanent and to sign a prolific but obscure Argentina-born Paragguay striker from Chile, Lucas Barrios.

The "football to remember" these players began to deliver more and more often was primarily based on an incredible amount of movement and the willingness to work together. When Borussia were in possession, there were always two or three players you could pass the ball to. When the team lost the ball, two or three players would attack the opponent before he could play a proper pass. One is tempted to argue that Klopp got rid of all the stars because stars rarely have the discipline, the hunger and the lungs to make this kind of football work. But the coach refutes this notion by pointing towards the obvious inspiration. "This football does work with stars — in Barcelona," he says. "They have won the World Cup, the European Championship and the Champions League and each of them has 15 or 20 million in the bank, but they run as if there's no tomorrow. That is the model. If you ask the young lads, the new generation of players that is coming up right now, they will say their ideal is football as played by Barcelona. They will say this is what football should look like."

It was football that yielded results — the team finished sixth in Klopp's first year, fifth in his second — but above all it won the fans back. They appreciated that the players gave their all in every game, they liked the new team-spirit that was almost palpable and they could identify with all those young and enthusiastic players like local boy Kevin Grosskreutz, who ran more than 13 km in every game and still owned a season ticket for the South Stand.

Still, nobody was prepared for what would happen this season. Or almost nobody. "I knew we could play at a very high level," says Klopp. "That became apparent very early on during the pre-season preparation. We all said, 'Wow, that's unbelievable — we have made some really good new signings.' For very little money we had acquired really good quality." The Polish striker Robert Lewandowski was signed from Lech Poznán for 4.5m Euros, but a 21-year-old midfielder by the name of Shinji Kagawa joined from Cerezo Osaka in Japan for only 350,000 Euros, while the defender Lukasz Piszczek came from Hertha in a free transfer and Mario Götze was called up from Borussia's own Under-18s. 

In early August, Dortmund played a pre-season friendly against Manchester City, of all clubs. Kagawa and Götze were the best players on the pitch and Borussia defeated a team that had just spent 120m Euros on new players with ease, 3-1. Klopp chuckles as he thinks back to that supposedly uneven match-up. "We knew we could play like that," he says. "What came as a surprise is that such a young team would deliver so consistently."

The ultras have reached Signal Iduna Park, sorry, the Westfalenstadion, and Daniel Lörcher has found the hip-hop guys. One of them wears a Kevin Grosskreutz shirt which the player himself sells through his homepage. "We're all Dortmund boys," it says, referring to one of The Unity's favourite songs. Some of the ultras here are good friends with Grosskreutz, they have stood on the terraces and gone to away games with him.

"All of this is almost too good to be really happening, too perfect to be true," says Daniel. "This whole season is surreal." It rarely happens that a football club as big as Borussia is represented on the pitch by a young, hungry and inexpensive team that is hugely popular with the fans. And it also rarely happens that a football team plays breathtaking attacking football game after game and dominates more or less every opponent it comes up against. But when both these things happen at the same time, well, that probably deserves to be called "surreal". In fact, there are people who have been following the club since the 1960s who claim they've never seen anything like it, that this is the best Borussia team of all time. 

Daniel, who used to be a good player himself, ponders this for a moment. Then he says, "No, it isn't the best-ever team. Not yet. But perhaps in two or three years. We have to bolster the squad in a few selected spots, we need a stand-in up front and we need a back-up man for Sven Bender in defensive midfield." But he agrees that the city loves this team like hardly any side before and he also agrees that the unshaven, passionate coach is the main reason for all this. "When Klopp was signed, I was sceptical, because I thought, 'Here comes the TV coach, who's trying to please everyone,'" Daniel says, alluding to the fact a good deal of Klopp's nationwide popularity stems from his eloquent and entertaining appearances as a television pundit during big international tournaments. "But then he asked us for a meeting. He came and talked to us and I realised this guy is for real. He really is this emotional and yet also very rational, totally committed football man."

Suddenly, a loud cheer goes up in the beer garden that is just a stone's throw away from the ground. It is echoed inside the stadium, where many fans have already gathered around the bratwurst stalls to watch the early afternoon's football action on mounted television sets. Daniel and the two hip-hop guys turn their heads, trying to find out what happened. But of course they already know what must have happened before somebody with a radio tells them that, yes, Bayern Munich have scored against Bayer Leverkusen after barely seven minutes of play.

It would be supremely ironic if Bayern were to bring Borussia closer to the Bundesliga title by beating Leverkusen on this sunny afternoon in the spring of 2011. Because in a way the serious problems that befell Dortmund in the late 1990s and the new millennium, the difficulties that led to that make-or-break day in March 2005, had their roots in Bayern's exalted position in German football.

One week after the Freiburg game, at Easter, Ottmar Hitzfeld would look back upon his years as coach of Borussia and tell the Süddeutsche Zeitung, "We thought that our aim should be keeping pace with Bayern, winning the league every year and playing in the Champions League. But that is impossible. It would be the completely wrong approach to plan something like that again now. Bayern will remain the number one."

In contrast to the leagues in Spain, Italy and England, the Bundesliga has failed to produce two or three big clubs that compete for the title every season. Germany really only has Bayern Munich. Every few years, a club will come along that challenges Bayern and becomes a temporary rival — from Gladbach in the 1970s, through Hamburg and Bremen in the 1980s to Dortmund and then Leverkusen in the 1990s. But the unwritten rule says that such a club will compete only for a few years before it has to regroup, making room for the next contender.

The president Niebaum and the business manager Meier (and, as his statement implies, to a degree the coach Hitzfeld) attempted to break this mould in the 1990s. They felt that Borussia had the tradition and the appeal and the fan base to become another Bayern Munich. All that was needed was money. Lots of money. The simple fact that there was never going to be enough financial backing in a region that may have football passion in spades but no economic power whatsoever didn't deter Niebaum and Meier and the clubs' countless fans. They wanted to believe — and so they believed.

When the club went public in 2000, two years after Hitzfeld had left Dortmund for Bayern Munich, Borussia seemed to be awash in money. But unbeknownst to almost everybody, the club was already more than 70m Euros in the red. In a classic ruinous cycle, the cash that came in was needed to pay off debts run up by huge transfer fees, star players' salaries and all those ill-conceived subsidiaries that bled money. Then more debts were incurred to sign new stars who made sure more cash kept coming in. 

Finally, Dortmund struck a deal with Molsiris Ltd, an investment company owned by a large Frankfurt bank. Under the agreement, Borussia sold the stadium to the investors for 75m Euros and then bought it back in annual leasing instalments. That deal gave the club enough cash to pay for the enlargement of the ground while the Molsiris investors, many private citizens from all walks of life, would one day pocket a nice profit. It sounded like a win-win deal. It became a lose-lose situation when the expensive team at last stopped delivering.

In 2004, Borussia failed to qualify for Europe and coach Matthias Sammer was fired. Five months later, Niebaum and Meier admitted that the club had debts of almost 120m Euros. The president was forced to step down and Meier was told his contract would not be extended. In the short term, however, he was needed to help a group around the local entrepreneur Hans-Joachim "Aki" Watzke save the club, since only Meier knew his way around all the myriad deals and loans and debts. Watzke and his financial experts managed to come up with a plan that might keep the club alive. There was only one problem: Borussia could no longer pay the leasing instalments to Molsiris. During an emergency meeting scheduled for 14 March, 2005, the investors had to agree to a deferring of these payments — otherwise Borussia Dortmund would be bankrupt with immediate effect.

"I was optimistic that these investors would agree to the plan," says Jens Volke six years later. "I thought they wouldn't want to be responsible for destroying such a big club, in which case they also would never have seen their money back." But the meeting at Düsseldorf airport went on for hours and hours. "And slowly we began to ask ourselves: what if?" Volke remembers. "What if those people vote no? Some of us said, 'Borussia cannot be demoted to, say, the Oberliga, simply because this club has too many fans.' Imagine 20,000 Dortmund fans travelling to some village ground in the fourth division! Impossible."

This consideration, although certainly valid, will have been of very little importance to the investors. But after more than six hours of questions and explanations, the Molsiris investors agreed to the bailout plan Watzke and his men had presented. At 3.30pm — the time when most Bundesliga games kick off on a Saturday — Borussia was saved.

Volke and the two handfuls of other devoted fans who were holding out in the cold were not communicating by phone with anyone inside the building, so they only learned of the outcome when somebody stepped outside. "Strangely, I can't remember who that person was," Volke says. "And I don't think anyone was celebrating when the news made the rounds. We were all happy but quiet. I guess that's because the situation was so unreal."

Meanwhile, in Dortmund, Daniel Lörcher's boss kept his promise. As soon as radio reported Borussia's rescue, he walked over to his new employee and told him the worst was over. Daniel, too, didn't celebrate loudly. He just took a deep breath, let it out slowly and felt immense relief. When his work day ended, he immediately drove to his favourite pub in downtown Dortmund, where about 20 or 30 fans, among them Jens Volke, were raising their glasses to the fact that one of the greatest football cities in the country still had a football club. 

It wasn't until three years later that Jürgen Klopp would learn how serious the situation had been. "The first time it occurred to me that Borussia Dortmund might not be that well-off was when I received the first offer from them," he says with a smile. "It was worse than what Mainz was willing to pay me in the second division!" Klopp laughs and slaps his thigh. "I said, well, I guess that must be an error. But we sorted that out." 

Mats Hummels wouldn't hear how near Borussia had come to the brink until a day in March of last year, when he paid a visit to a Borussia fan club in Belgium. "Aki Watzke was driving the car," he recalls. "And during that journey he told me a few things about this whole story. It was only then that I realised how dramatic the situation had been and also how much luck Watzke and his men needed to save the club."

But of course Daniel Lörcher, Jens Volke and most of the other fans know how terrifyingly close their beloved Borussia had been to the abyss and remember that day six years ago vividly — which makes the championship season double sweet and so perfect you sometimes wonder who has scripted it. As the ultras carry their gear through the turnstiles, for example, another cheer erupts. Bayern have scored again and Leverkusen, who never do well in Munich, are falling apart, unable to cope with the pressure.

That's what some experts predicted would happen to the young Dortmund team — but it never did. Just take the away game in Munich in February. It was Bayern's last chance to get back into the race and it appeared to be a really good chance, because Dortmund, like Leverkusen, had a terrible record in Munich — and they were missing one of their few experienced players, the goalkeeper Roman Weidenfeller. But his substitute, a 22-year-old Australian by the name of Mitch Langerak, who had never played for the first team before, didn't make a single mistake, while his outfield players ran so much that Bayern's feared superstars Arjen Robben and Franck Ribéry were regularly up against three men, making it seem as if Borussia had more players on the pitch than Bayern. Barrios scored, Bayern equalised. Then Dortmund's playmaker Nuri Sahin, the 22-year-old Germany-born Turk, who has been playing for Borussia since he was 11 years old, scored with a wonderful swerving shot. And to make this another perfect day, the 18-year-old Götze then whipped in a corner that was headed home by none other than Mats Hummels, confirming the defeat of the club that had sold him because it thought he wasn't good enough to perform at the highest level.

A few weeks after the Bayern game, Hummels extended his Dortmund contract until 2014. He is aware that a season like this will make some rich clubs take notice of the assembly line of talent in Dortmund. But he says he doesn't care. "We have discussed the possibility of offers from big clubs among ourselves," he says. "But we know that we have got something very special here. Of course, if Barcelona come in with an offer, you can't expect people to tell them to bugger off. But for the time being, we've decided to stay together. We have a really great team spirit, in part because so many of us are about the same age. And we're so young that we can play here for a few more years just to see where all this will lead."

For starters, it seems to lead to the league title. While Daniel is being interviewed on the stadium's closed-circuit television about the need to keep ticket prices down so that even the unemployed or teenagers can support their team, Bayern are beating Leverkusen 5-1. If Dortmund win this game against Freiburg, they will have opened up an eight-point lead and for all practical purposes wrapped up the title, completing what many are already referring to as a miracle or, as the former coach Hitzfeld will call it over the Easter weekend, "a fairy tale".

And the game fulfils all expectations. Or rather: it is just like all the other Dortmund games have been this season. The opposition is a good, well-organised team — Freiburg are in eighth place, don't concede many goals and have the Bundesliga's second-best scorer — and yet they are completely, hopelessly overmatched. Dortmund do everything faster, smarter, better and more passionately. It's almost as if they are playing a lower-league team in an early-round Cup game. Just watching it takes your breath away.

After 22 minutes, Hummels — a centre-back, remember! — plays an elegant chipped pass with the outside of his right foot into the path of Marcel Schmelzer, the 23-year-old left-back. Schmelzer goes to the byline, pulls the ball back and Götze scores from 10 yards with his left foot. Three minutes before the break, Hummels stops a rare Freiburg attack and ... can this be true? ... plays another delicate through-ball with the outside of his foot. Lewandowski is clean through on goal, rounds the goalkeeper and makes it 2-0. (Two days later, Hummels will be standing in the offices of a Dortmund internet company, fending off various premature congratulations from starstruck trainees. When somebody asks, "How come you're suddenly spraying passes like Franz Beckenbauer?" Hummels grins and cheekily replies, "I've been playing these passes all season. But people only notice them when they lead to goals.")

The game is decided — and so is the title race (despite Hummels's protestations). After about an hour, Dortmund have had sixteen shots on goal, while Freiburg have only one. On the platform in front of the South Stand, Daniel and another ultras leader jump up and down while the fans sing the Pippi Longstocking song about winning the championship. Can this day get any better? Of course it can — because in this season, everything is perfect. On 77 minutes, a Lewandowski pass beats the offside trap, Götze bears down on goal and then squares the ball off for a teammate, who puts the ball away for the third goal, right in front of the South Stand and all those delirious fans. The goal-scorer is, of course, that Dortmund boy who used to stand among the ultras, Kevin Grosskreutz. 

After the game, Borussia's players run a lap of honour — and even the Freiburg supporters give them a standing ovation. It begs the question if this might indeed be the best team this club has ever had, even better than the side that won the Champions League. "I don't know about that, because we're talking about a totally different kind of quality here," says Klopp. "And I'll leave such comparisons to people who have actually seen all those sides. But what I can say is that this team certainly has the biggest potential of all the teams Borussia Dortmund has ever had. But potential becomes quality only through character, knowledge and shared experiences. The eventual quality of this team cannot be determined right now." Is one reason for this that many things can still go wrong in the larger scheme of things? "Oh, everything can go wrong," replies Klopp. "Our players are very interesting for other clubs right now, because this here is the most exciting project in the international game at the moment. We are watching young players who are not part of an established team, who don't get carried along because all the other players around them are very experienced. Instead we are watching a group of highly talented players who push each other. But of course it's difficult to keep them together. We have to be prepared for the day when someone leaves. This is one danger. There are some others. I'm not clairvoyant, I don't know what will happen." 

(The "someone who leaves" will turn out to be Nuri Sahin. It isn't Barcelona, though, whom he can't tell to bugger off — it's Real Madrid. And as promised, the move finds Klopp prepared, because he's already signed Nürnberg's playmaker Ilkay Gündogan, who is 20 years old and, like Sahin, grew up in the Ruhr area the son of Turkish parents.) 

One danger Klopp does not mention is one that would be first on the list at most other clubs, namely raised expectations and unreal ambitions. But only six years after a March day no Dortmund fan would want to live through again, the chances are very slim indeed that Borussia will once more fall victim to the trappings of megalomania. "If somebody thinks we have to win the league next year, because second place is nothing and third place means a shitty season," says Klopp, "then this someone is not to be helped. The time is ripe for healthy and realistic expectations." And you sense he doesn't mean just the fans and the journalists. Because he adds, "The really unbelievable thing is that these players' greatest quality lies beyond the pitch. It's their character." 

At about 8.30pm, the first of the ultras arrive back at the pub where they had started some four hours earlier. They know their club will almost certainly win the league now, but they are not boisterous, not rowdy. Most of them drink mineral water and are perfectly sober, though visibly exhausted. A man who is unusually old for an ultra, probably in his mid-thirties, is sitting on the sidewalk and taking sips from a bottle of fruit juice. He slowly shakes his head.

"Six years ago, nobody would have thought we would come back like this," he says. "This is almost impossible to grasp."

Which reminds the one single person among this group who is not an ultra that there is something he has wanted to ask Daniel all along. How can Daniel say that the season is surreal, how can he make all those statements about the team — when he has never seen it? He is always facing the fans, isn't he?

"Watching people's faces tells you a lot," Daniel says with a smile. Then he adds, "And I do look over my shoulder quite a lot. Because you have to look back from time to time, don't you?"