5-2. Five-two. FIVE-two. No matter how many times those two numbers echoed through the minds of millions, they just didn't make sense. After two closely fought 1-0 wins by the champions Borussia Dortmund in the league, everyone expected another tight game — and, above all, a reaction from Bayern Munich. But instead of reasserting their claim to the throne, Bayern were humiliated in front of 75,000 fans at Berlin's Olympic Stadium. For the Reds, the biggest defeat in a final, ever. For the Black and Yellows, the first ever double in their 103-year history. For both sides, almost too much to take.

"It's like something from another planet," said the Borussia keeper Roman Weidenfeller, who was nursing a painful rib-injury after coming together with Mario Gómez and could barely hold up the cup after the final whistle. "A double … ", stammered the hoarse Dortmund manager Jürgen Klopp. "It's the most incredible thing that's ever happened to me." He was "lost for words", the 44-year-old told reporters. "The result will speak for itself."

But it didn't, at least not in a familiar language. The two digits shouted and screamed into the ears of bewildered Bayern supporters, but they had little idea what they meant.

As is usually the case with severe trauma, a coping mechanism kicked in, Bavarian loyalists tried to convince themselves that what didn't look real couldn't possibly be real, or at the very least, couldn't be the whole story. Was it an elaborate ploy, perhaps? Was Jupp Heynckes simply repeating the former West Germany coach Sepp Herberger's famous trick from the 1954 World Cup? He played a weakened side against Hungary in the group stage and lost 3-8, only for a full-strength team to beat the same opponents 3-2 in the final. Herberger had lured the much-fancied Magyars into a false sense of security, the not-altogether-plausible narrative goes.

It's conceivable a similar theory will emerge with more credibility if Bayern recover to beat Chelsea in the Champions League final in Munich on Saturday. But some felt it might be better if they don't turn up for their "home final" at all. "It's a very important game, in terms of confidence," Heynckes had said before. "It won't be easy to get this out of our heads but we have to," a dejected Bastian Schweinsteiger said afterwards.

Still, there was good and bad news from a Bayern perspective. The good: Luiz Gustavo will be suspended against Chelsea. The Brazilian midfielder suffered from a double brain-freeze to give away the ball twice and allow Shinji Kagawa to score the opener inside 159 seconds. In the stands, Sir Alex Ferguson and Mike Phelan looked on excitedly. Their reported transfer target said he didn't know about his future, and reports that the Japanese midfielder had boarded a flight to Manchester that same night proved inaccurate. The truth is, Ferguson could have looked at a number of exciting Dortmund players who would all improve his side immediately. The centre-backs Mats Hummels and Neven Subotic were colossal again, as was the Polish right-back, Lukasz Piszczek, who has emerged as a Real Madrid target.

Luiz Gustavo, by contrast, steadfastly refused to pick up any runners or move into any sort of recognisable positions. He was at fault again for Dortmund's third goal, another classic sucker punch featuring telepathic interplay from Kagawa and Robert Lewandowski. The irrepressible Polish forward went on to score a hat-trick with two more goals in the second half.

Bayern had actually come back rather well after their early set-back. Arjen Robben expertly dispatched a penalty — Weidenfeller had brought down Gómez and had to be substituted afterwards — and Heynckes' men were playing well enough for Philipp Lahm to claim that Bayern had been "the better side in the first half". They created chances and passed it well but whenever Dortmund had the ball, the Bavarians were in a state of panic.

Which neatly brings us to the bad news: Jérôme Boateng will not be suspended against Chelsea. The former Manchester City defender had one of those games in which he seems only half-awake, as if he'd just stumbled out onto the tarmac after a 16-hour flight in economy. Four minutes before the break, he needlessly brought down Kuba Blaszczykowski, who was going nowhere in the corner of the box. As brainless challenges go, it was up there with John Terry's brave knee into the back of Alexis Sánchez.

Hummels, the former Bayern man who had fought tooth and nail foil their attempts to bring him back to Säbener Strasse, dispatched the penalty past Manuel Neuer. On a better evening, the Bayern goalkeeper would have saved the shot. On a less horrible, devastating evening, he wouldn't have gifted Dortmund the fifth goal by dropping a tame ball.

"They've had one chance and scored three goals," moaned Heynckes, with some justification. "Our defensive behaviour was catastrophic. If you don't concentrate from the start, you don't deserve to win. We've only got ourselves to blame."

"Individual mistakes" became the preferred explanation later on. Statistically, the performance was indeed an aberration — Bayern only conceded 22 goals in 34 Bundesliga games — but the disaster at the back couldn't quite explain the awfulness in the middle, where Bayern suffered a total system breakdown in the second half. "This was not bad luck nor a coincidence, this was an embarrassment," Karl-Heinz Rummenigge said in front of sponsors and VIPs at the midnight banquet. "Every Dortmund goal was like a slap in the face today." It must have made for encouraging viewing for Roberto Di Matteo.

Bayern will have to think long and hard about their tactical deficits before they go head to head with Dortmund again. No other team exploits their weaknesses with so much frightening precision. "It's not about knowing how to do it, it's about doing it," said Klopp, in recognition of his side's superhuman work-ethic. "The boys did everything I asked of them – and more."

The fifth consecutive defeat by Klopp's men, and the most emphatic, has shaken the Bavarians' belief in their inherent superiority. It's less easy to gauge how the defeat will impact on next week's Champions League showdown, however. The Sky Deutschland pundit Jens Lehmann felt that this drubbing might actually benefit the Reds. "I can't see them making this many mistakes again," said the former Arsenal goalkeeper. "They'll play with anger and even more determination next week. I'm rather optimistic about their chances." It was a minority view on the night, to be fair. This week's build-up in Munich will now come with a hefty dose of trepidation.