London - Wimbledon champion Roger Federer admits he was shocked to hear Rafael Nadal had opted not to defend his Olympic gold medal, but he expects his great rival to return to action soon.
Nadal pulled out of the Games last week after claiming he was "not in condition" to compete following a recurrence of the knee problems which have troubled him for several years.
The 26-year-old struggled with the injury throughout his French Open title-winning campaign and looked well short of his best in a stunning Wimbledon second round defeat against unheralded Czech Lukas Rosol.
The Spaniard's latest fitness issues led some to question whether he will be able to continue competing at the highest level, but Federer believes Nadal will find a way to get back in action in time for the American hard-court season, which starts soon after the Olympics and culminates with the US Open.
"It was a big surprise to see Rafa pull out of the Olympics as the defending champion from four years ago," Federer said.
"It is a big blow to the tournament but he must have his reasons. I don't know if it was his knee or his preparation wasn't good enough.
"I thought it was more his preparation and that would mean he is probably close to coming back on tour. He is only missing maybe a week or two here."
Asked if Nadal had talked to Federer about dealing with his injury problems, the world No 1 added: "I haven't spoken to him. I don't think he will call to discuss his problems with me! We are close but I wouldn't do that with him either.
"I'm sure he would have wanted to be here (at the Olympics). I wish him a speedy recovery and hopefully we will see him on the tour again soon."
Nadal's absence is a significant boost to Federer's hopes of winning singles gold for the first time and the 30-year-old, who returned to world No 1 after winning Wimbledon earlier this month, is strong favourite to triumph in the Olympic event, which gets underway at the All England Club on Saturday.
But Federer is adamant Novak Djokovic and Andy Murray, beaten by Federer in the Wimbledon final, will pose a strong challenge.
"It's exciting for the rest of the field regardless of Rafa is here or not," Federer added.
"Novak has a good chance after such a wonderful run over the last year and Andy Murray has played so well at Wimbledon recently."