Dutch defender Jenson Seelt has been ruled out for the remainder of Sunderland's Championship campaign after picking up a knee injury in the weekend defeat by Southampton.
The 20-year-old will undergo tests to assess whether he will require surgery to repair the issue.
Seelt has played 17 games for the Black Cats since his arrival from PSV Eindhoven last summer.
He only made one senior appearance for the Dutch club before leaving.
Team-mates and fellow defenders Niall Huggins and Dennis Cirkin are also currently sidelined with long-term injuries.