Wigan Athletic manager Roberto Martinez says he fears Ivan Ramis suffered a cruciate knee ligament injury against Fulham on Saturday.
Ramis was stretchered off after twisting his knee in a tackle with Dimitar Berbatov, as Wigan came from behind to draw 1-1 at Craven Cottage.
The Spanish defender is yet to undergo scans which will determine the full extent of the problem, but Martinez is predicting a grim diagnosis.
"I wouldn't want to say anything before seeing the scans, but I fear the worst," he said.
"He has damaged the ligaments in the right knee and the signs are not great.
"I expect the worst, cruciate ligament. We are going to take him to hospital on the way back.
"Those injuries go from six to seven months, but obviously it is impossible for me to tell yet because we need to get the scans.
"The manner he has done it, the way he has felt the knee opening and the pain he has got in the top of the patella tendon, I do fear the worst." Fulham manager Martin Jol was frustrated by his team's inability to kill the game off, having led through a goal from veteran midfielder Giorgios Karagounis.
"It is always the same story," Jol said.
"You go one up and you need another goal but cannot score another goal and then you are vulnerable.
"It is easier said than done but when you are 1-0 up you still have to dominate the game.
"We had a little problem to contain them and they had players in the pockets but we are a big team at the back.
"But we needed a second goal and we did not score a second goal. It was the same against Southampton when we needed second goal and didn't score and they scored an equaliser.
"We have a problem in our balance but we have quality and that will pull us through but we have to score two goals.
"Last year, if we scored one goal it was decisive. This year most of the time, it wasn't decisive."