Everton midfielder Marouane Fellaini will miss the rest of the season with an ankle injury.
Fellaini will undergo surgery next Monday after aggravating the injury in Saturday's Premier League win over Sunderland.
Fellaini, 23, missed the FA Cup fifth-round loss to Reading at Goodison Park and manager David Moyes confirmed the news after the game.
The Scot explained: ''Marouane is going to be out for the season now, he will have an operation on Monday.''
It is the second successive year an ankle injury has brought a premature end to Fellaini's season.
Fellaini, a club record £15 million signing three years ago, was out of action for around six months after an ankle operation in February 2010.
Moyes added: ''Everybody who has watched us will tell you he has been a key player for us and Tim Cahill will probably miss two or three weeks as well.''
Australia midfielder Cahill also missed the game with a foot injury.
The absence of the influential pair will be a major blow as Everton look to improve upon their mid-table position in the Premier League.