Scottish goalkeeper Craig Gordon says a knee injury may force him to retire at the age of 30.
Gordon was signed by Sunderland for nine million pounds in 2007 - at the time the highest fee ever paid by a British club for a goalkeeper - but was released at the end of the 2011/12 campaign.
A 40-cap Scotland international, Gordan has been without a club since his departure from the Stadium of Light and, while he is not prepared to give up on making a return to playing just yet, Gordon has already begun planning for his future by taking up a coaching role with Dumbarton.
"I'm not ruling out playing again but as it goes on, increasingly it gets harder," Gordon told the Daily Record.
"I've had a couple of surgeries on it, but it's definitely not back to 100 percent yet.
"Hopefully I can get back to playing with a bit of pain. It's about getting to a stage where I can get what I need to out of the knee.
"I definitely won't be playing again this season. That's part of the reason I wanted into coaching, you don't know when the end might come for playing.
"I'm certainly not ready to throw in the towel just yet but it's been a long time and I don't know where I'll be going in the future."
Gordon has attempted to kick-start a coaching career by working with Scottish First Division side Dumbarton on an ad-hoc basis.
"(Dumbarton player-manager) Ian Murray called me to ask if I wanted to help and to get some experience," Gordon said.
"I was delighted to take him up on his offer.
"I would prefer to aim for management but you need the experience of coaching and going through the ranks."