Bayern Munich’s Bundesliga lead was cut to five points as Marcus Ingvartsen’s late goal earned Union Berlin a draw at the home of the reigning champions.
Fielding a largely second-string side because of injuries, illness and the upcoming Champions League tie with Paris St-Germain, Bayern led through Jamal Musiala’s strong run and finish.
But with four minutes to go, Ingvartsen bundled home at the back post.
Bayern are now on 65 points, five ahead of second-placed RB Leipzig.
Leipzig won 4-1 at Werder Bremen.
Both teams have six games still to play.
Bayern were missing nine players in total on Saturday, including top striker Robert Lewandowski.
They will be hoping to have some of them back as they look to overturn a 3-2 deficit in Paris in the second leg of their Champions league quarter-final tie with PSG on Tuesday
