Sunderland striker Steven Fletcher has undergone ankle surgery to repair ligament damage, the club confirmed on Thursday.
The 26-year-old Scottish international was injured in Scotland's 2-1 defeat to Wales in a UEFA World Cup qualifier on March 22 and was carried off the pitch on a stretcher.
He has missed the Black Cats' last three Premier League matches and will not play again this season.
Fletcher signed with Sunderland from Wolves in the summer for 12 million pounds and remains the club's leading scorer, despite his injury, with 11 goals in league play this season.
The club hopes Fletcher will be fit to begin next season, but his absence leaves them short on attackers for the remainder of this term.
"I don't want to be critical, but if you're a team that wants to stay up, or a team who wants to win the league, I think you need five strikers," manager Paolo Di Canio said. "You can't afford to be short on strikers. Wherever you are in the league, you need to score goals."
Sunderland currently sit in 15th place in the Premiership, three points clear of the bottom three after a convincing 3-0 win over derby rivals Newcastle United last weekend.
The Black Cats will look to give themselves even more breathing room when they tangle with Everton at the Stadium of Light on Saturday.