Sunderland are awaiting news on Jordan Pickford after the in-form goalkeeper injured his knee on Boxing Day.
The 22-year-old has been in eye-catching form despite the Black Cats' struggles this season and any absence would be a major blow for manager David Moyes.
While Pickford completed the full 90 minutes of the 3-1 defeat at Manchester United he was in some discomfort after the match and was sent for scans.
On Wednesday morning the club were still awaiting the results and have yet to confirm if he will miss the New Year's Eve trip to Burnley.
While that is considered an important match, there are reports Pickford is facing an even longer spell on the sidelines.
Former Arsenal keeper Vito Mannone is standing by if required.
The Italian started the season as the side's number one but fractured his elbow in August, opening the door for Pickford to stake his claim in impressive fashion.
Pickford has become a full England squad member under Gareth Southgate and has been linked with big money bids in January.