Roger Federer should play until he is 60 if he wants to, according to former top- ranked tennis player Ilie Nastase.
The Swiss 17-time Grand Slam champion has slipped to sixth in world rankings and won only one title this year, prompting talk that he is a spent force at 32.
Romania's Nastase, the former bad boy of tennis, believes Federer, pictured, should not listen to the naysayers, however.
"I wish people wouldn't say Roger Federer has to retire," the former French and US Open champion said. "I think he should play for as long as he wants.
"I don't agree with those people who say that you should retire when you're past your absolute best or prime.
"No, Federer doesn't have to prove anything, he can play to 60 if he wants."
Federer, who has spent a record 302 weeks as world No1, is still one of the biggest draws in tennis, Nastase said, even if he has fallen behind players such as Rafa Nadal and Novak Djokovic.
"If Federer wants to carry on playing, no one is going to say: `No, we don't want Federer to play.'
" He is going to retire when he feels like it. I don't think he has to retire just because he is no longer the world No1."