Hapless Cologne sank deeper into relegation trouble when they were thrashed 4-0 by Mainz 05 in the Bundesliga on Tuesday.
The contest was over before halftime as Eugen Polanski, Mohamed Zidan and Nicolai Mueller scored in an 18-minute spell in the first half, sending Cologne to their fourth defeat in five games in which they have conceded 17 goals.
Adam Szalai added the fourth and Cologne's only consolation was that their nearest rivals also lost.
Hertha Berlin also took a step closer the second division as they lost 2-1 at home to Freiburg, who continued to climb away from trouble, and Augsburg lost 3-1 at home to VfB Stuttgart.
Augsburg are 15th in the 18-team table with 30 points from 30 games, one place and one point above Cologne in the relegation playoff spot. Hertha are 17th with 27 points.
(Writing by Brian Homewood; Editing by Pritha Sarkar)