Cronulla NRL backrower Reece Williams is recovering in a Sydney hospital following surgery to remove a blood clot from his spine after he collapsed during a NSW Cup game on Saturday.

Williams, who had an operation to remove a blood clot from his brain last year after being concussed in an NRL match against Parramatta, was carried off during the Sharks reserve grade team's match against Shellharbour after making a tackle.

He underwent surgery on Wednesday.

The incident has cast doubts on whether the 2007 City Origin representative will be able to continue his career, with doctors ruling that the 24-year-old should be sidelined indefinitely.

Sharks coach Ricky Stuart visited Williams on Thursday and said he was in good spirits.

"Reece is a tremendous person and an extremely talented player," Stuart said in a statement.

"Everyone in rugby league wishes him a speedy recovery. Regaining his health is his number one priority and the Sharks will support him all the way."

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