Diarra suffered a serious injury in their Capital One Cup victory over Cheltenham on Tuesday night.
"Our team news is that Alou Diarra got injured the other night and is not involved in the squad," manager Sam Allardyce said of today's Premier League clash with Stoke.
"It's more serious than we expected and it looks like an ACL reconstruction, unfortunately.
"That will probably finish his season, that is a big blow to us in squad terms. He was hoping to forge his way into the side this season but, obviously with the injury, now that won't be the case."
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