Rafael Nadal has revealed that he still has doubts over his knee as he prepares to make his comeback from a six-month layoff next week.

The 26-year-old has not played since he was defeated in the second round of Wimbledon by Lukas Rosol, and while he insists that he trusts his doctor's advice, he has admitted that he is "afraid" of how his knee will react.

Nadal told Canal+: "I have my doubts. It's normal. We are talking about a knee, so of course I am afraid to see how it is going respond.

"But I can only trust my doctors and believe in myself and that everything will be all right."

Nadal is hoping that next week's exhibition tournament in Abu Dhabi will help him prepare for the Australian Open in January.