Mamadou Sakho is set for a scan to assess the extent of the injury which forced him off on a stretcher in the narrow defeat to Tottenham Hotspur.
A late screamer from Christian Eriksen settled the tie in the visitors' favour, by which time Palace had already lost the imposing centre-back to a nasty looking injury.
“We think it’s a ligament, but which one we don’t know," the gaffer said in his post-match press conference. "We certainly hope it’s not the cruciate but it could be the medial or the lateral, but it certainly looks like a hyper-extension of the knee and we wait and see what the scan shows.
"With such a short space 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.”
Watch the full press conference for free HERE.