Play was stopped for five minutes and the Ecuador winger required oxygen as he left the pitch on a stretcher after defender Kirk Broadfoot appeared to fall on the winger's leg. He will now have an operation on Wednesday morning.
"He's gone to hospital and it looks like it’s a dislocation or a fracture," he told Sky Sports. "It’s a bad one and it will keep him out for a long time."
The manager later confessed during his post-match press conference that he feared Valencia could be out for the rest of the season and compared the injury to the one suffered by Alan Smith against Liverpool in 2006.
"As soon as I saw the Rangers player waving to the bench we knew it was a bad one."