Rio Ferdinand admits he is reluctant to commit his future to Manchester United and may consider retirement when his contract ends in the summer.
Ferdinand, 34, says he has not begun negotiating a contract extension at Old Trafford, with his fitness playing a major part in his future decision.
Sir Alex Ferguson recently backed Ferdinand to play into his late thirties, but the defender is not as confident in his ability to continue his career.
"It is always good to hear the manager say things like that," Ferdinand told Inside United. "But you have to take every week and month as it comes.
"The best thing I can do is to look at it at Christmas, and then again in the summer, to see how I'm feeling and go from there. But hearing the manager say things like that definitely puts the spring back in your step."
Ferdinand's omission from Euro 2012 allowed him to recover from a number of injuries that plagued him last season, and he says the extended break could be key to playing on next season.
"I'll have a better idea of [whether the break was a good thing] in December or January when the games start coming thick and fast," he said. "That is when it really hits you and you know the hard work really has to start. I'll probably get a better gauge of where I'm at fitness-wise and the benefit of having the summer off then."
If Ferdinand decides to continue playing for United, it is believed that the club will offer him a one-year extension to his current deal.