Crystal Palace boss Sam Allardyce hopes to have on-loan Liverpool defender Mamadou Sakho back before the end of the season - but admits the player may have suffered a serious injury.
Sakho was carried off during Palace's 1-0 defeat to Tottenham on Wednesday.
He fell awkwardly after challenging Spurs striker Harry Kane for the ball in the second half.
The 27-year-old joined Palace in January, signing on loan until the end of the season.
Allardyce, who had said after the game he suspected it was "ligament trouble", said on Thursday: "I'd like to think it is not serious and he will get back before the end of the season but I'm not sure.
"We are unable to say what the extent of the injury is at the moment. It didn't look to clever the way the knee hyperextended.
"Let's wait for the scan, will probably have to contact Liverpool depending on how serious the damage is. We can't speculate on if, when and how and the seriousness of the injury."
Sakho has made eight appearances for Crystal Palace, helping them move up to 12th and seven points clear of the relegation zone.