"The boys in the stands have been singing for weeks that Borussia will be German champions," read the black and yellow display from the Borussia Dortmund fans up in the third tier, "and their courage is unwavering!"

And why not? After six years of Bavarian dominance in Germany's top flight, Dortmund travelled south with a two-point lead over Bayern Munich and just seven games to play. They'd already beaten Bayern at home in November and victory, or at least avoiding defeat, in the Allianz Arena would have put the Black and Yellows in the driving seat and made them favorites to win their first Bundesliga title since 2012.

And when Mahmoud Dahoud hit the post seven minutes in after Jacob Brun Larsen and Marco Reus had combined to tear through Bayern's right flank, those fans seemed justified in sensing that this Borussia Dortmund was different. Whatever happened in Munich today, at least there wouldn't be a repeat of the 6-0, 4-1 and 5-1 thrashings suffered on their last three visits.

And indeed, it wasn't 6-0, 4-1 or 5-1. This time, it was 5-0. Dahoud's effort was as good as it got because after that, in every area of the pitch and in every individual battle, Bayern Munich were so vastly superior that it was simultaneously impressive and depressing. 

From Joshua Kimmich crunching into Jadon Sancho the moment the English teenager received the ball, to Kingsley Coman accelerating past Lukasz Piszczek as if he wasn't there, to Robert Lewandowski pouncing on Dan-Axel Zagadou's error to score the second, Bayern were quicker, sharper, stronger, harder.

Magnificent Martinez

In midfield, Javi Martinez was imperious, single-handedly dominating Axel Witsel and Thomas Delaney with his timing, interceptions, tackling and passing. Five minutes before half-time, he showed he could shoot as well, smashing in Bayern's third from the edge of the box. If it wasn't already over, it was now, and it was fitting that Martinez delivered the blow.

From start to finish, Bayern were mentally alert in their pressing, precise in their passing and clinical in their finishing. For the first time this season, they demonstrated those traits against high caliber opposition – on paper anyway – having been shown their limitations by the likes of Ajax and Liverpool in the Champions League and also by Dortmund when the two teams met earlier in the season.

But the Borussia Dortmund which had won so spectacularly at the Westfalenstadion was nowhere to be seen. Nor was the Borussia Dortmund which had opened up a nine point lead by Christmas. Or the Borussia Dortmund which had battled until the end to secure vital late wins against Stuttgart, Hertha Berlin and Wolfsburg recently, confident in their ability to find a way no matter what.

Visitors look callow

Instead, this Borussia Dortmund looked physically smaller than Bayern, their collective lack of experience in these title races rendered bare against battle-hardened opponents who, despite their problems this season, have been there and done it. The black and yellow banner held by the boys up in the away end could easily have referred to the black and yellow boys on the pitch, battling in vain against men in red.

"We were catastrophic, our defending was catastrophic, we didn't exert a single ounce of pressure," said captain Marco Reus. "We can't accept that. We have different expectations. We can't complain when we play like that and get beat."

An objective glance at the Bundesliga table shows that Dortmund are only one point behind Bayern with six games to play – a position Lucien Favre would doubtless have taken at the start of the season. But the Swiss coach will surely look at his own role in this calamity and wonder why he left his best player, Reus, isolated up front and why he left his best playmaker, Mario Götze, on the bench.

But as part of such a collective failure, would it have really made a difference? "If we play like that against Mainz, it will be just as difficult," said Favre, looking ahead to the coming weeks, where both teams' remaining fixtures suggest that there will be twists and turns yet. "But before wanting to win, win, win, we have to start playing." 

And to start playing, those Borussia Dortmund players will have to rediscover their courage and belief. The top tier of the Allianz Arena would be a good place to start looking.