Britain's Tim Henman admits he will quit at the end of the year, if his form and fitness do not improve.
Henman loses his British number one ranking to Scottish teenager Andrew Murray when they are updated this Monday, and the 31-year-old knows his time in the game's elite is nearly over.
Injury ruined 2005 for Henman and since returning to the ATP Tour the former world number four has failed to rediscover his old form.
"Call it unfinished business, if you like, but I need to know, once and for all, whether my body and mind will let me play on,” he told The Mail on Sunday.
"If they do, I've got two or three years left. If they don't, then I'll be calling it a day."
Henman has thrilled the British public with his exploits at Wimbledon over the years, but never progressed beyond the semi-final stage, and now feels his chance to win the tournament has gone.
"Let's be honest, it's looking increasingly unlikely now isn't it? This year, for example, for the first time in nearly 10, nobody will be thinking I'm a contender,” admitted Henman.
"It's taken me a long time to understand it but when people ask why I haven't won Wimbledon, the truth may be something none of us will be happy about. Maybe I just wasn't good enough.
"Maybe reaching the semi-finals and getting to fourth best in the world rankings was as good as it gets for me. Maybe we all just have to accept this."
To carry on beyond this year, Henman says he must start to enjoy playing tennis again.
"It's not a decision I have to make now but I've set myself targets and if I don't reach them then, come the end of the year, I'll be saying: `Thanks very much, I'm getting out of here',” he added.
"I've got to be enjoying my tennis again and, for that to happen, my back's got to hold up and I've got to get back into the top 20. I need that as a minimum.
"I'm 31, I've got two daughters and a wife, which means that anything over three weeks away from home makes it miserable for me. And my body's falling apart.
"If it doesn't go to plan this year and I realise that I can't achieve the goals I've set for myself, then I'll stop.”