World No. 1 Roger Federer is backing defending Olympic champion Nicolas Massu in his bid to gain a wildcard entry to the Games in Beijing in August.

The Chilean star won both singles and doubles gold medal in Athens four years ago but having slipped down the rankings to 123, he is now ranked too low to get a direct entry into the 64-man Olympic tournament.

But six places in the draw are awarded by the International Tennis Federation's Olympic Committee, at its discretion, and Federer said on Wednesday that Massu should be top of the list.

"He's the defending champion - if he doesn't get one anymore, I don't know who will get one," Federer said at the French Open in Paris, where he reached the semifinals on Wednesday.

"Yeah, I'm the first guy to completely agree with that. I hope it's in a positive way for Nicolas, because what he achieved back in Athens, winning singles and doubles, maybe it's never going to happen again.

"I know maybe his ranking dropped, but nevertheless, he achieved great things four years ago, and I think he should be compensated with a wildcard this year."