Sunderland captain Lee Cattermole will be out for at least four months after undergoing hip surgery in the U.S., manager David Moyes has said.
The news came as a significant blow to Moyes, who has been without one of the club's most consistent performers in recent seasons for much of his reign on Wearside.
The setback arrived after a lengthy treatment process which eventually got to the root of the problem.
Moyes said: "It's a big blow because we have had hernias, we have had epidurals, we have had other things done but, by all accounts, we have found a tear in his cartilage in his hip which has now been repaired."
Cattermole, who joined the Black Cats in a £6 million switch from Wigan during the summer of 2009, has been a key figure in the club's successful survival fights over the last four years.
But he was last able to take to the field for the 3-2 Premier League defeat by Crystal Palace on Sept. 24.