Sunderland striker Steven Fletcher has undergone ankle surgery after damaging ligaments on international duty last month.
The 26-year-old Scotland international has missed the last three games for his club and is out for the season.
Fletcher remains Sunderland's leading scorer in a campaign that has seen the Black Cats drop into a relegation battle.
The £12m summer signing from Wolves has scored 11 Premier League goals.
His absence represented a major blow to then manager Martin O'Neill with the club fighting for Premier League survival.
O'Neill revealed at the time that he was hopeful Fletcher would not need surgery, but admitted it was a possibility if the ankle did not settle down with treatment and rest.
The Ulsterman was replaced by Paolo Di Canio on 31 March, with the newcomer well aware he would be without the man most likely to fire the Black Cats out of trouble.
Even without Fletcher, Sunderland won 3-0 at derby rivals Newcastle on Sunday with goals from Stephane Sessegnon, Adam Johnson and David Vaughan to move the club three points clear of the relegation zone.