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Korea Republic international Lee struck four minutes before the break after pouncing on a defensive blunder by the lacklustre visitors.

Lee then doubled the hosts' lead on the hour, turning beautifully in the box to finish a superb attacking move that left the Bayern defence frozen to the spot.

Bayern, missing eight players with injury including top scorer Harry Kane, pulled a goal back through Leroy Sane in the 87th minute.

It remains in top spot on 33 points, four ahead of Bayer Leverkusen, which was a 2-0 winner at Augsburg, but looked far from itself.

Mainz, which sits sixth, had won three Bundesliga matches in a row prior to a 4-3 defeat at Wolfsburg last time out, but it is a team that seemingly saves its best for facing Bayern.

While it lost 8-1 at Allianz Arena in its previous league meeting with Bayern, Mainz has now reeled off four straight home wins against the team starting the day at the top of the Bundesliga – on each of those occasions, that side was Bayern.

On the back of feeling frustrated at seeing his streak ended, Kompany insisted there was no time to dwell on the result, ahead of hosting RB Leipzig, which will be Bayern's last match in 2024.

"We played against a team with a lot of life and spirit, they were prepared to fight for every moment," Kompany said.

"From our side, there was not a lack of fighting. We did that to the best of our ability. Today we were just not at our best.

"This game, we can't play it any more, it's done. We'll use it to build a fire for next week. That's the only way to give an answer.

"We can't win this game in Mainz this year, but in the future, we're looking forward to it."

The clash with Leipzig is followed by a three-week break from league action, as the Bundesliga hits pause until mid-January for its winter break.