Newcastle manager Steve McClaren has revealed striker Emmanuel Riviere may require surgery on his injured knee.
Riviere, 25, returned home early from the Magpies' preseason tour of the United States after taking a knock in training.
The Frenchman was left out of Newcastle's 2-2 Premier League draw against Southampton on Sunday because of the injury and McClaren concedes he may need an operation.
"I think Manu Riviere's knee was painful after training so he might have to have surgery," McClaren told the Newcastle Evening Chronicle. "We are investigating that."
Riviere scored just one goal in 23 league appearances last season following his £5 million move from Monaco.