Crystal Palace manager Steve Kember has admitted goalkeeper Matt Clarke could be forced to retire from football this week.
Clarke missed most of last season with a knee ligament injury and has suffered a related problem.
He started the first four games of the season but has not been in the squad since August and sees a specialist this week.
Kember said: "The knee is troubling him. He will see a specialist again. There is a possibility he might not be able to play again.
"Is it ever going to be right? I'm not too sure."
Clarke missed most of last season with a knee ligament injury and has suffered a related problem.
He started the first four games of the season but has not been in the squad since August and sees a specialist this week.
Kember said: "The knee is troubling him. He will see a specialist again. There is a possibility he might not be able to play again.
"Is it ever going to be right? I'm not too sure."