Burnley boss Sean Dyche fears Robbie Brady's knee injury is serious after he was stretchered off with his leg in a brace following an awkward collision at Leicester City on Saturday afternoon.
The Republic of Ireland man hit the turf after a 27th-minute challenge on Harry Maguire and looked to be in some distress as he left the field.
He'd been his team's best player in the first 25 minutes and both club and country will now sweat on the extent of the injury.
"It looks more serious than not serious to me; that’s all I can say," Dyche told the club's website.
"He’s gone off to hospital, so we need to find out more before I can give the full facts.
"It’s a blow because Robbie has been excellent lately. He’s a good character in the group and he’s been building with his performances."
The Clarets have made a terrific start to the campaign but fell to a 1-0 defeat at the King Power Stadium.
Dyche's exploits had attracted the attentions of Everton, who failed to lure him to Goodison Park. Burnley are facing into a hectic festive period and will feel Brady's loss.
For Ireland, the play-off hammering against Denmark means there's no World Cup in Russia to look forward to in 2018, but Martin O'Neill will hope one of his key men isn't hampered by a lengthy absence as he looks to pick up the pieces of that Aviva Stadium disaster.