Adam Matuszczyk injured his ankle in Friday's training session and will be sidelined for three weeks.
Matuszczyk collided with teammate Simon Terodde during FC Koln's last training session before Saturday's match against Hoffenheim.
At the beginning it was feared to be a fracture, which would mean that Matuszczyk would not be able to play for two months. The first diagnosis was incorrect and Matuszczyk will only be out for three weeks.
-"In any case, it's still a big blow for us," said FC Koln coach Frank Schaefer.