Socceroo Bailey Wright could be sidelined for the rest of the season after picking up an ankle injury.
Wright is set for at least two months out after hurting his ankle in Sunderland's 1-0 win over Oxford United last weekend.
"It didn't look good at the time and tests have confirmed he will miss eight to 12 weeks," Sunderland manager Phil Parkinson told the club website.
"It's a blow for the squad, but we have good options available in his absence."
Wright only joined the Black Cats on loan from Bristol City last month.
Sunderland are fifth in League One and pushing for a return to the Championship.
The 27-year-old has been unfortunate with injury in recent seasons, playing only nine games this season and just 15 in the 2018/2019 campaign.