Crystal Palace defender Mamadou Sakho could be out for the season after he was stretchered off during Wednesday's 1-0 loss to Spurs.
The 27-year-old is on loan at Palace from Liverpool and has impressed with his performances at the heart of the Eagles' defence.
However, he fell awkwardly during the second half at Selhurst Park as he tried to challenge Harry Kane and received treatment before being carried off.
Palace manager Sam Allardyce told the club's website: "We think it's a ligament, but which one we don't know.
"We certainly hope it's not the cruciate but it could be the medial or the lateral. It certainly looks like a hyper-extension of the knee and we wait and see what the scan shows.
"With such a short amount of time left we won't know if any of our defenders will get fit again and we might have to rely on Damien [Delaney] and Martin [Kelly] for the remaining games of the season.
"The last place we would have wanted an injury today was at centre-back but, in saying that, we're very blessed that we have five centre-backs at the club at the moment and we could have been in a terrible situation with Scott Dann, James Tomkins and now Mama Sakho injured.
"Normally we wouldn't have had any centre-halves left to put in but at least we have Martin Kelly, who has been excellent and was outstanding again today, and the experience of Damien Delaney to step in.
"We're going to need them from now until the end of the season."
Sakho has been an influential figure as Palace have pulled clear of the bottom three, although their unbeaten run came to an end on Wednesday, Christian Eriksen scoring to give Spurs a 1-0 win after the defender had departed.