Bayern Munich s defender Niklas Suele (L) reacts after a missed chance during the German first division Bundesliga football match between FC Bayern Munich and Eintracht Frankfurt in Munich, southern Germany on October 3, 2021. AFP
Goalkeeper Kevin Trapp kept Frankfurt in the game with a series of spectacular saves before Filip Kostic hit a powerful low shot past Manuel Neuer for the winning goal in the 83rd minute.
Bayern came into the game on a run of nine wins in all competitions _ scoring at least three goals in each game _ and with the same starting lineup from its 5-0 rout of Dynamo Kyiv in the Champions League on Wednesday.
Instead, Frankfurt enjoyed its first away league win at Bayern since November 2000.
From the start, Bayern dominated in every area of the game except one _ scoring past Trapp. The Frankfurt goalkeeper denied Robert Lewandowski, Thomas Muller and Leon Goretzka early on and leaped to keep out a bungled clearance which was nearly an own-goal.
Bayern got the breakthrough when Goretzka shot low past Trapp from the edge of the area in the 29th. Frankfurt needed three minutes to level. Martin Hinteregger had been at fault for losing the ball on Bayern's goal but made up for it with a towering header past Neuer off a corner from Kostic.
Trapp produced another highlight reel of saves in the second half, with a reflex stop from Lewandowski's header the standout. When it seemed Frankfurt was barely clinging on to a point, Djibril Sow beat Bayern substitute Marcel Sabitzer to a loose ball and played in Kostic for the Croatian to shoot under Neuer for the winner.
Bayern sent Neuer up as an extra attacking player in the final minutes but couldn't break through the Frankfurt defense and Trapp.
``It was a lot of work today,'' Trapp told broadcaster DAZN. ``Really, really intensive, and well done to the team.''
Earlier, Taiwo Awoniyi scored twice in four minutes to turn the game around as his Union Berlin team beat Mainz 2-1. Awoniyi was at Mainz on loan before signing for Union from Liverpool, and Mainz's scorer Marcus Ingvartsen was a former Union player.