Matt O'Riley will undergo surgery after being forced off injured on his Brighton debut.

The former Celtic midfielder, 23, hobbled off after just nine minutes against Crawley in the Carabao Cup.

O'Riley - who had completed his move just one day earlier - suffered a serious ankle injury as a result of a rash challenge by Jay Williams.

The midfielder was unable to put weight on his ankle after the match and it has now been confirmed he will be sidelined as he requires surgery on the injury.

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Brighton boss Fabian Hurzeler admitted he is unsure how long O'Riley will be unavailable but confirmed it was a serious injury issue.

"Like we expected, it's a bad injury. He needs surgery on his ankle," said Hurzeler. "I can't say how long we expect him to be out.

"We have to look at how the rehab will go but of course it is a tough one for us.

"We will try to support him the best way we can and get him back on the pitch as fast as possible.

"Let's hope he will be back soon."

Crawley boss Scott Lindsey has since apologised for the tackle. He commented: “Maybe we were a bit aggressive, maybe the referee missed it (the challenge) and I would like to apologise.

“I wouldn’t want anyone to be hurt. We are both passionate about the game and we wish Brighton all the best in the next round.”