Sunderland midfielder Lee Cattermole has been ruled out for four months following hip surgery.
The 28-year-old is currently in the United States, where he underwent the operation earlier this week.
Cattermole has been plagued by a longstanding hip problem and has made just two appearances this season.
Manager David Moyes said: 'We're going to be without Lee for four months and it's a big blow.
'He's out there in the States just now and is coming back in the next few days.