Paddy McNair has been ruled out of action after rupturing his anterior cruciate ligament.
The Northern Ireland international, who joined Sunderland from Manchester United in the summer, suffered the injury during the club’s 3-0 win over Hull City on Saturday.
The incident occurred when the midfielder closed down Curtis Davis on the edge of his own penalty area.
McNair, 21, faces a lengthy spell on the sidelines but will now focus on returning to action as quickly as possible.