Bayern’s first home defeat in 12 months left the title race wide open with Bayern remaining on top with 14 points.
Hoffenheim's Sargis Adamyan scored his first two Bundesliga goals to stun hosts Bayern Munich 2-1 on Saturday and earn their maiden win in Munich.
The 26-year-old Armenian striker scored either side of a Robert Lewandowski goal as Bayern suffered their first league loss and crashed back down to reality four days after their 7-2 demolition of Tottenham Hotspur in London in the Champions League.
Bayern's first home defeat in 12 months left the title race wide open with Bayern remaining on top with 14 points, ahead on goal difference of Freiburg, who drew 2-2 with Borussia Dortmund, and RB Leipzig and Bayer Leverkusen, who drew 1-1.
Schalke 04, on 13, can take over the lead with a win against Cologne later on Saturday, while Borussia Moenchengladbach, also on 13, take on Augsburg on Sunday.
The visitors had a golden chance after four minutes but Adamyan, who joined this season from second division Regensburg, hesitated in his one-on-one with keeper Manuel Neuer to allow Jerome Boateng to clear at the last moment.
Bayern did not come near their midweek European form and apart from some good chances in the first half never showed the kind of clinical finish that saw them fire seven goal past Tottenham.
The Armenian made amends in the 54th minute when he fired in from a tight angle to surprise Neuer after Corentin Tolisso had lost possession in his own half.
Lewandowski grabbed his 11th goal of the campaign with a well-timed header after Bayern upped the pressure in search of an equaliser.
Adamyan, however, crowned his first start for Hoffenheim with his second Bundesliga goal in the 79th, beating Neuer once more with a low shot, to give his team their first win in Munich and their first three points since late August.