Second-placed RB Leipzig crashed 3-0 at Werder Bremen on Saturday to suffer a shock successive Bundesliga defeat and allow Bayern Munich the chance to extend their runaway lead to a mammoth 13 points.
The Bavarian giants started the weekend 10 points clear in their seemingly unstoppable march to a fifth straight German league title, which will become lucky 13 if they win at Borussia Moenchengladbach on Sunday.
Having begun their first Bundesliga season with a record 13-match unbeaten run, Leipzig's title challenge has collapsed following four defeats in their last seven games, taking a meagre seven points.
"We started well, but then you concede your first goal with their first shot," said Leipzig's coach Ralph Hasenhuettl.
"We can't rely upon the momentum, that rub of luck, like we could in the first half of the season."
After losing 1-0 at home to Wolfsburg last weekend, Leipzig folded again in Bremen as Werder's Austria international Zlatko Junuzovic scored their first goal and set up their second.
The dead-ball expert crashed home a curling, thunderbolt goal from outside the area on 34 minutes, then provided the free-kick which saw relegation-threatened Bremen double their lead.
Junuzovic spotted Florian Grillitsch unmarked on the edge of the area and the attacking midfielder beat Leipzig goalkeeper Peter Gulacsi on 59 minutes.
Leipzig's humiliation was complete as their defence capitulated when Bremen's Fin Bartels led a counterattack and Florian Kainz tapped home on 90 minutes.
All three Bremen goals were scored by Austrians -- an extra-bitter pill for RB, who are sponsored by Austria's energy drinks giant Red Bull.
Leipzig are now just three points ahead of third-placed Borussia Dortmund after Dortmund's lacklustre 1-0 home win over Ingolstadt on Friday.
Pierre-Emerick Aubameyang, the league's top scorer, hit the winner.
Anthony Modeste claimed a hat-trick as Cologne broke into the top six with a 4-2 win over Hertha Berlin.
The Frenchman needed less than 30 minutes to claim his second hat-trick of the season after also netting three against Hamburg last October.
Japan striker Yuya Osako gave Cologne an early lead, then set up Modeste's first goal on 35 minutes.
His second followed two minutes later as the Frenchman showed some ice-cool finishing to make it 3-0 to the hosts.
Hertha's top scorer Vedad Ibisevic pulled a goal back on 50 minutes when he converted a penalty after Cologne's goalkeeper Timo Horn fouled Berlin midfielder Niklas Stark in the area.
Modeste wrapped up his hat-trick by finishing off a superb Cologne counter on 63 minutes, then Hertha's US international John Brooks headed home to make it 4-2 with 20 minutes left.
Fresh from their mid-week Champions League exit at Atletico Madrid, Bayer Leverkusen suffered a 1-0 defeat at Hoffenheim thanks to Sandro Wagner's second-half goal for the hosts.
Mario Gomez scored Wolfsburg's winner for the second week running when he slotted home on the stroke of half time to seal a 1-0 victory over bottom side Ingolstadt.
Mid-table Augsburg were held to a 1-1 draw at home to Freiburg.
Greek defender Konstantinos Stafylidis equalised for Augsburg in the first half after Freiburg's Florian Niederlechner had converted a penalty.
Hamburg remain third from bottom but picked up a valuable point in their goalless draw at Eintracht Frankfurt.
Hamburg are eight points away from an automatic relegation spot and their current placing of 16th carries a two-legged play-off against the team which finishes third from top in the second tier to decide who plays in the top flight next season.