Sunderland forward Duncan Watmore has damaged his cruciate ligaments and will miss the rest of the season, Sportsmail understands.
The 22-year-old suffered the knee injury during Saturday's 2-1 win over Leicester City after tangling with Christian Fuchs.
Watmore was forced off on a stretcher and a scan on Monday revealed the extent of the damage, keeping him out for the remainder of the campaign.
It is a blow for the England Under-21 star, who is also likely to miss next summer's European Championships.