Patrik Schick scored late in the game as Bayer Leverkusen beat Borussia Monchengladbach 1-0 on Saturday afternoon.
The result was more bad news for Gladbach, who face Manchester City in the Champions League Round of 16 in 10 days.
They tumbled to 10th place and have now gone six games without a win.
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Marco Rose's team have lost their last three league games in a row since the coach stunned fans by announcing his decision to join Borussia Dortmund next season.
Neither team had any real attacking spark in the first half, with Leverkusen having a bit more possession but failing to threaten.
The Foals briefly picked up the tempo after the break and came close before Flick scored on the rebound following keeper Yann Sommer's save of a Moussa Diaby shot.
Leverkusen are fifth on 40 points, three behind Eintracht Frankfurt, who drew 1-1 against VfL Stuttgart. VfL Wolfsburg are third on 45 points following their 2-1 loss to Hoffenheim.
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