Bayern Munich defender Holger Badstuber could miss the start of next season after suffering another thigh injury.
The Germany international, whose career has been riddled with injuries, made his comeback in August after 20 months out with a knee problem.
A month later the 26-year-old hurt his thigh, needed an operation, and only returned in February.
Now he needs more surgery, keeping him out for three or four months, after injuring himself against FC Porto.
Badstuber played the full 90 minutes as Bayern beat the Portuguese club 6-1 to win 7-4 on aggregate and reach the Champions League semi-finals.
"Obviously I'm very disappointed at the moment," said Badstuber.
"But despite it all I'm remaining positive and I'll be back again fully fit. I know everything will be done for me at Bayern so I can come back as an important part of the team."
Chairman Karl-Heinz Rummenigge said: "We're so sorry for Holger. He worked so hard towards his latest comeback - and now this."
Badstuber has only managed 111 Bundesliga appearances in total, having spent his whole career at Bayern.