Sunderland's in-form forward Duncan Watmore will miss the rest of the season after a scan showed he has damaged cruciate knee ligaments, British media reported on Monday.
The 22-year-old was carried off in the 83rd minute of Saturday's 2-1 Premier League win over Leicester City after colliding with fullback Christian Fuchs.
The club has yet to officially confirm the scan results.
Sunderland manager David Moyes has already lost Paddy McNair and Lynden Gooch to long-term injuries but while the former has also been ruled out for the season, the latter does not require surgery on his torn ankle ligaments.
"The team is getting better but, unfortunately, we've picked up another injury with Duncan," Moyes was quoted as saying on the club website.
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"It doesn't look great. Duncan has been playing well."
Sunderland are still in the relegation zone with 11 points from 14 games but have hauled themselves off the bottom of the table with three wins in their last four league games.
