Bayern Munich defender Holger Badstuber is facing a length spell on the sidelines.
The Germany international featured from the start in Sunday's 2-1 defeat to Bayer Leverkusen but was forced to stay behind in the dressing-room at half-time due to a muscular problem.
Badstuber has yet to undergo further examination to determine the exact extent of the knock, but Bayern coach Jupp Heynckes fears the defender could be out of action for a long time.
"Holger has picked up a muscle injury. It's either a sprain or a muscle tear," Heynckes said.
Meanwhile, Luiz Gustavo also left the pitch in the second-half after picking up a knock and though his problem does not appear to be serious, he is a doubt for Wednesday's DFB-Pokal clash with Kaiserslautern.