Karim Adeyemi and Julian Ryerson netted in either half at the Allianz Arena to ensure the visitors secured their first Der Klassiker win since as far back as 2019.
England captain Harry Kane appeared to have given Bayern a glimmer of hope with one minute remaining of normal time but the striker’s header was subsequently ruled out for offside by referee Harm Osmers.
The result leaves defending champions Bayern 13 points adrift of runaway leaders Leverkusen, who came from behind to beat Hoffenheim in dramatic fashion earlier in the day.
Leverkusen’s incredible late comeback came after Xabi Alonso committed at least another season to the club, putting to bed rumours that the Spaniard could jump ship to take charge of either Bayern or Liverpool in the summer.
Bayern head coach Tuchel – who departs at the end of the season – cut a forlorn figure in the aftermath of Bayern’s latest disappointment and appeared to concede the title to Alonso’s unbeaten Leverkusen side as he reflected on the loss.
‘Overall, the game wasn’t played at a high level. It was an average game,’ Tuchel told Sky Germany in his post-match interview.
‘Unfortunately, we never adapted to that. From the lack of pace to the lack of passion. It’s hard to explain.’
Tuchel felt Bayern’s defeat at the hands of fierce rivals Dortmund came somewhat out of the blue.
The former Chelsea boss added: ‘We thought in the last few weeks that we wouldn’t get to the point where we would give away a game like that.
‘We had something completely different in mind, but we just didn’t manage it.’
Asked whether the title race was now effectively over, Tuchel replied: ‘Yes, definitely. Congratulations to Leverkusen.’
Joshua Kimmich described Bayern’s performance as ‘incomprehensible’ and anticipated a ‘difficult’ week for the squad ahead of their clash with Heidenheim.
‘I wonder how we could perform like that in a game like this. It’s completely inexplicable to me, it’s completely incomprehensible,’ the Bayern midfielder told Sky Germany.
‘In the second half you had the feeling that nothing was at stake. It was like a friendly.
‘We players should go home and question ourselves. It doesn’t matter who is in the team.
‘It will be difficult next week against Heidenheim and of course in the Champions League.”
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