Bayern Munich’s troubling start to Thomas Tuchel’s reign continued as the champions slumped to a 3-1 defeat to Mainz at Mewa Arena on Saturday.
Die Roten looked on course to bounce back from their UEFA Champions League exit by Manchester City in midweek but were sensationally pegged back by Tuchel’s former side as Bayern’s winless run stretched to four games.
Sadio Mane gave Bayern a deserved first-half lead from close range, but Mainz showed signs of promise and built on such encouragement after the break when Ludovic Ajorque erased the lead.
Leandro Barreiro put Mainz in front 17 minutes from time and Aaron Martin’s fine strike soon after ended Bayern’s lead to give Borussia Dortmund the chance to go on top on the day.
Bayern threatened an early breakthrough when Mane coolly slotted past Mainz goalkeeper Robin Zentner in the 15th minute, only for his goal to be ruled out for offside.
But the visitors took the lead just before the half-hour mark, Joao Cancelo’s cross from the left wing leaving Mane with the simplest of headers at the back post.
However, the home side were good value after the hour mark.
Yann Sommer could only parry away Lee Jae-sung’s effort and Ajorque was on hand to nod in from yards out.
This was only the beginning for Mainz.
Eight minutes later, Karim Onisiwo parried Josip Stanišić when he met Ajorque’s flick and then teed up Barreiro, who confidently slotted home.
Martin then got the better of Bayern and fired a left-footed shot into the bottom right-hand corner from the edge of the box with 11 minutes remaining.