Sunderland striker Fraizer Campbell could miss the bulk of next season if he needs a second knee operation.
The former Manchester United frontman damaged his cruciate ligament in August last year and was nearing a comeback when he twisted his knee in training ahead of the Barclays Premier League clash with Manchester City.
Manager Steve Bruce said: "We do fear for him. We think the surgeon needs to go and have a look inside his knee again and if it does need repairing again, then Fraizer is going to miss the best part of next season as well, which is an even worse blow for us and more importantly, for the kid.
"Nobody could have done his rehabilitation better than he did, but he fell over and twisted it on the Friday before we played Manchester City.
"The way it's going for us at the moment, we do fear that the boy might need another operation, and that could rule him out for the best part of next season as well."