History was made in the Allianz Arena on Sunday as Bayer 04 Leverkusen recorded their first away win at FC Bayern Munich since 1989. Goals from Stefan Kießling and Sidney Sam, either side of a Mario Mandzukic effort, did the damage for the away side, and in the process ended the Bavarians' quest for a remarkable ninth straight win in the Bundesliga this season.
On paper this had looked like a home banker. Bayern had momentum on their side with the maximum 24 points in the bag ahead of kick-off, while the Werkself had started the year in a somewhat stop-start fashion, their last result a 2-2 home draw with 1. FSV Mainz 05.
Coached by a man known for his defensive instincts, it was no surprise to see how Sami Hyypiä's Leverkusen set their stall out, as three holding midfielders protected a back four that rarely strayed too far ahead of the 18-yard-line.
The problem for Bayern, unsurprisingly dominant in possession, became clear when they attempted to push into more advanced areas, as a cluster of Leverkusen shirts surrounded the man with the ball.
Mandzukic, the league's joint top-scorer, was a peripheral figure at best. In home games gone by this term, the Croatian international had dazzled spectators with the quality of his movement and passing combinations with the rest of the Bayern attack.
On this occasion, however, he, Thomas Müller and David Alaba, starting in place of the injured Franck Ribery, were forced down one cul-de-sac after another. Aside from a close-range header well saved by Bernd Leno, the Reds had very little to show in attack during a frustrating opening period.
Leverkusen's gameplan was working to excellent effect, and even though they hadn't shown too much ambition going forward, it was they that stole the lead just before the break, with a goal that has become their trademark in Hyypiä's time at the helm.
Bayern had committed men forward in attack, and when possession was turned over, a lightning-quick break ended with André Schürrle finding Kießling to stroke a cool finish past Manuel Neuer, ending a perfect half for the away side.
The scoreline was a shock to most of the 69,000 spectators, but it was Bayern's lack of cohesion and rhythm that was decidedly more worrying. A response was needed in the second half and it arrived courtesy of three substitutions.
Xherdan Shaqiri and Arjen Robben both entered the fray, taking to the wings to stretch the Leverkusen back four and open up gaps for their teammates to exploit. There remained, however, the nagging feeling that, without Ribery, Leverkusen didn't fear the home side's attacking menace, and although Robben linked up well with Philipp Lahm, the final pass was unusually lacking.
Nevertheless, with Bayern's winning run under threat, the pressure began to build, and they hauled themselves back into the game with thirteen minutes left. This time it was the third substitute that made the difference, as Claudio Pizarro picked out a precise cross for Mandzukic to glance past Leno.
Now the noise level began to climb. Leverkusen were camped on the edge of their box and Schürrle and Kießling were then withdrawn, as Bayer focused their efforts on consolidation. It seemed as though they would settle for a point, but a sting in the tail was then provided by Sam in dramatic fashion.
Daniel Carvajal found possession high up the pitch, and might have been forgiven for playing for time, but instead crossed for substitute Sam - the only Leverkusen player in the box - to head in the winner via the help of a deflection from Jerome Boateng, stunning the home crowd into silence.
Bayern remain top of the table with a four-point cushion over second-placed FC Schalke 04, but there will be concern about another lacklustre display after the unconvincing 1-0 win in Lille in the Champions League.
For Leverkusen, on the other hand, the confidence they gain from this win - 23 years and one week since Marek Lesniak's solitary strike secured their last triumph in the Bavarian capital - could be what really gets their campaign going, as they moved up to fifth.