Celtic defender John Kennedy has suffered a relapse in his long-term battle to recover from a serious knee injury.
The 22-year-old this week signed a one-year extension to keep him at the club until the summer of 2007, but has been out of action since sustaining a cruciate ligament injury in March 2004.
But the Scotland international broke down in training on Thursday, although Celtic manager Gordon Strachan is hoping the problem is not too serious.
Kennedy will now fly to Colorado in the United States next week where he hopes leading surgeon, Richard Steadman, will give him the all-clear for a return to training.
Strachan said: “John has suffered a reaction and I just hope it is nothing back to where it was.
“When I looked at it, I just thought it was a kick and John thought it was more of a twist. So he’s going to be tested.
“I spoke about his attitude on Thursday and he is going to be tested again.
“It is also a test for the club as well, because, when it happened, the training stopped for 20 minutes and it was hard to get going because he is held in such high esteem.
“John was hoping he was on his way back. I hope it is something that is not as serious as some thought it was yesterday.”