Martin Paterson has torn the cartilege in his knee, meaning he will miss three months of action.
The striker twisted his knee off the ball in Tuesday night's defeat at Barnsley, and may now not be available until the new year.
An operation on the knee last night confirmed the damage.
"We were hoping he had just nicked it, which would have been two to four weeks, but it's the worst-case scenario and coming on the back of the news of young Chris McCann it's a body blow for both the players, first and foremost," manager Owen Coyle told Sky Sports News.
"That's my concern. It's not great news when your young players, who I believe are top players, get injuries and our thoughts are with the players.
"It will be hard for them to take, but we will make sure they get the best rehabilitation and support system in place and I do know they will both come back bigger and stronger and better players for the football club.
"They are both young players who have been terrific since I have been at the club and both of them have got a big role to play when they come back."
Paterson and McCann will now both be absent from first team duties for at least two months each, leaving Burnley with a big hole in their squad. However, their absence will give players such as Steven Thompson, Jay Rodriguez, Joey Gudjonsson and Kevin McDonald a chance to taste Premier League action.The dead leg suffered by Brian Jensen at Bransley is not expected to keep him out long-term, and the giant goalkeeper may even be available for Saturday's trip to Spurs.
This article was written for FansOnline Burnley.