On the official Borussia Dortmund website is a picture of two men walking purposefully towards Terminal E at Düsseldorf airport. They look determined and confident yet inside they must be feeling sick. Their names are Hans-Joachim Watzke and Dr Reinhard Rauball and they are on their way to a meeting with more than 400 investors of a company called Molsiris in an attempt to stop the club going bankrupt.

It is 14 March 2005 and the club owe around €130m. They are the Leeds United of German football, having spent ludicrous amounts on players (€25m on Márcio Amoroso from Parma stands out), selling their ground and borrowing vast sums of money in the hope of continued Champions League participation. However, having lost to Bruges on penalties in the 2003 Champions League qualifiers and then missed out on Europe altogether the following season, their plan unravelled at an astonishing pace.

And so it all came down to Watzke and Rauball who having both joined the club in the preceding months to sort out the mess, found themselves having to convince the 400 investors why they should accept diminished returns in the hope that the rescue plan would work.

The meeting lasted for hours and hours. In Dortmund – and elsewhere in Germany – fans were listening nervously to the radio for news on whether their club had been saved. In the end, when afternoon had entered evening, it was announced that Molsiris, whose shareholders had all invested between €5–100,000, had agreed to save the club. After the negotiations, Rauball said: "I don't want to experience a day like today ever again in my whole life."

For Watzke and Rauball, however, the hard work had just started. The club's high earners had to be sold and wages slashed. So the following year Tomas Rosicky joined Arsenal and the Germany international David Odonkor moved to Real Betis. In 2007 another Germany international, Christoph Metzelder, left on a free because he could not agree a deal with the new, parsimonious, board. Metzelder signed for Real Madrid instead.

Even now, with the club on a more secure footing, the selling has to continue. On Tuesday morning it was announced that Mario Götze, the club's highly regarded attacking midfielder, will join Bayern Munich next season, a bitter pill for the club to swallow on the eve of their Champions League semi-final against Real Madrid. It is a seismic transfer that will test the resolve of everyone at the club, but with a talismanic manager, Jürgen Klopp, at the helm, Dortmund have the best chance of taking the blow on the chin and remaining a force next season.

After the 2007-08 season, when Dortmund finished 13th, the club looked destined for a decade or so of mid-table obscurity, or even worse with relegation a real possibility. But then, during that summer, they hired Klopp, or "Kloppo" as he is now known.

Hiring Klopp was not necessarily a straightforward decision. The then 40-year-old might have taken unfancied Mainz to the Bundesliga for the first time in the club's history but he was probably just as well-known for his work as a TV pundit for the public broadcaster ZDF and had earned the nickname TV-Bundestrainer (a national coach for the television).

Uli Hoeness at Bayern Munich was interested in hiring Klopp but in the end the board wanted more of a box-office name and chose Jürgen Klinsmann. There were also reports that Hamburg made Martin Jol their new manager instead of Klopp that summer because the Dutchman wore a suit to the interview and Klopp did not. There was even a debate about whether Klopp's scruffy appearance was undermining his authority. "If I were working as a bank manager I might have had a credibility problem looking like I do but I don't work as a bank manager, I work in football," Klopp said at the time. "I am nice to people and I like footballers. Why shouldn't I? We share the same hobby. But that doesn't mean that I am their best friend."

So Dortmund pounced on Klopp when others hesitated. The manager was delighted to join a "football city" (although he later revealed he thought the club's first contract offer "was a mistake" as it was less than he had earned at Mainz) and started rebuilding the squad. "I have the feeling that I will be able to work with the full support of the club here," he said in August 2008. "Life is too short to worry about things anyway. I am 0.0% naive. I know how it works by a business. If you don't do your job properly you lose your job."

There has not been any chance of Klopp losing his job at Dortmund. Borussia finished sixth in his first season in charge and then fifth in 2010, having sold the club's two top scorers, Mladen Petric and Alex Frei, in the process. The following season Dortmund won the Bundesliga, seven points ahead of Leverkusen, while still operating on a much smaller budget than most of their rivals. Dortmund had gone from the brink of bankruptcy to winning the league in six years, Kloppo style.

Mats Hummels, a Bayern Munich reject, cost €4m, Robert Lewandowski €4.5m, Neven Subotic likewise, Shinji Kagawa a measly €350,000. Lukas Piszczek arrived on a free while his compatriot Jakub Blaszczykowski joined for a reported fee of €3m. Nuri Sahin, Marcel Schmelzer, Götze and Kevin Grosskreutz all came through the ranks. Since that first league title win, Ilkay Gündogan has signed from Nürnberg for €4m and Marco Reus from Borussia Mönchengladbach for €17.1m.

No wonder Brendan Rodgers said recently that he wants to build Liverpool's squad "the Dortmund way" (although the way Sahin, now back at Dortmund after a short-lived loan spell at Liverpool "thanked God" he was no longer playing for Rodgers suggests the man at Anfield has some way to go to match Klopp's man-management skills).

But the Dortmund way is so much more than just scouting and bargain buys. Klopp has his own philosophy of what makes a squad competitive and it is one that sums up the ethos of the city they play in. "There are certain places where you have to conduct yourself and play football in a certain way, where you just can't be pleased with staying back and hoofing the ball upfield," he told the German football writer Uli Hesse last year. "There are certain places where, if you do that, people will say: 'If that is the way you are going to play then I won't go and watch you.'

"And Dortmund is one of those places. Here people demand that the team should play with the attributes that are closest to my heart: with a lot of feeling and with intensity until the very last minute. We want to play the kind of football people remember."

The players are certainly buying into the concept. "The players talk to each other about what to do if there is an offer from a big club but we know what we have something very special going here," Hummels has said. "If there is an offer from Barcelona then maybe you can't ask them to do one, but for the time being we have decided to stick together to keep this team together. The team spirit is fantastic and there are a lot of us who are the same age."

The news on Tuesday morning that Götze is signing for Bayern in the summer will test that spirit, especially in the same week they are taking on José Mourinho's Real Madrid. But Klopp is a superb motivator and will have his squad in the right frame of mind.

Most of the players adore him – and it is easy to understand why. He is enthusiastic, clever and funny. In fact, he is very much like Mourinho during his early Chelsea years. Klopp's press conference after the dramatic quarter-final win over Málaga was a joy to watch and his demeanour is such a contrast to Mourinho's current surliness that it is easy to bill Wednesday's first Champions League semi-final as the new Mourinho against the old Mourinho.

At the end of last week the Portuguese complained that Klopp was talking too much about Wednesday's first leg, to which the Dortmund manager responded by saying: "Mourinho says I talk a lot? That's what one of my teachers used to say. I'll shut up, then." 1-0 Kloppo; now for the real contest.