Burnley manager Brian Laws has revealed that Chris McCann will be sidelined for at least six months.
The midfielder missed a large chunk of last season after suffering two knee injuries and underwent surgery back in April.
However, he suffered a fresh setback during the Clarets' pre-season tour of Singapore and has now had a full, reconstructive operation.
McCann will be out of action until February at the earliest but Laws is convinced he will eventually return to full fitness.
"Chris needs a full reconstruction of the cruciate ligament. It is devastating news, not only for the football club but particularly for a player who has had a dreadful time trying to overcome anterior cruciate damage from over a year ago," he said.
"Chris has had niggles consistently over a period of time and it got to a point where we needed a second opinion.
"Unfortunately, that opinion is that he needs a full reconstruction and that we are now going to lose him for a minimum of six months.
"We must make sure it's clear to everyone that this is not career threatening and the plus is that he will make a full recovery and eventually be 100 per cent right and not looking at percentages on whether he will be fit or not."