Robin Soderling has revealed his determination to return to the ATP Tour despite his long-running battle with a viral infection.
The former world No 4 has not played a competitive match for 18 months after being diagnosed with mononucleosis.
The two-time French Open finalist admits he may never win his fight against the fatigue virus, and that he has suffered a number of setbacks in his bid to resume his tennis career.
"The hope, the hopelessness, then the hope again, then the hopelessness - that really kills me," said the 28-year-old Swede.
"I feel really good, then I start to practice, and then I think maybe in a couple of months I can come back and I really believe it. Then I do a bit too much and wake up one morning not feeling well again.
"In the past couple of months I had my best weeks and days, which gives me the hope, but I get setbacks and feel worse again.
"Overall it's getting better but I'm not as desperate to come back any more tomorrow. I will give it a shot, but I learned to live with the thought that maybe it will not be possible. Whatever happens, I will feel I did all I could.
"I feel I have at least five more years in me. But I still have a lot of things to be thankful for. The illness could have happened when I was 18 or 20. I was 27. Up to now I've had a good career."