Burnley midfielder Steven Defour will undergo knee surgery to repair damaged cartilage and faces a lengthy spell on the sidelines, manager Sean Dyche said.
Belgium international Defour has started 24 league games this season and played through pain in recent weeks before a precautionary scan revealed the extent of the injury.
"Defour will have an operation after seeing a specialist, it's a real blow," Dyche said. "It's come out of the blue, he'd been playing on and felt a soreness in his knee, he played with it for a few weeks.
"We took him for a scan, one of those ones you probably wish you wouldn't have, and it showed something that needs doing, it's a bit of cartilage. That's the way it goes.
"Unfortunately he's going to be out for some time... the specialist will have to sort it out and we'll wait and see what he says after the operation."
Defour, however, indicated in a post on Instagram that the injury is likely to rule him out for the rest of the season.
"Hard to take this one," he said.
"Really gutted I can't end the season in the way I wanted it. Promise to come back stronger for the new season."