After John Isner, now it is Roger Federer.

The world number one wants to see Rafael Nadal back on court again this year itself despite the Spaniard is suffering from a career threatening knee injury.

Eleven-time Grand Slam winner Nadal is likely to miss the forthcoming Davis Cup semi-final and even write off the rest of 2012.

"It's obviously not great news but one that was a possibility," said Federer.

"I'm not shocked about the news. I'm still hopeful that he'll be okay for the rest of the year," added the world number one.

Despite being one of the biggest rivals in tennis history for last eight years, who won 24 of the last 30 majors between them, Federer has shared that his relationship with Nadal is based on a lot of trust, as they know that the issues they share with each other do not reach anybody else.

He said, "There's no real secrets out there, because he knows and I know when we tell each other that stuff it doesn't leave the room. That's a nice relationship I have with Rafa. It's based on a lot of trust."

To elaborate this 'trust' further, Federer said, "I think it's quite personal except if one guy goes up to the other. But we're both very open and honest. When I ask him how he's feeling, he's not feeling well, he'll tell me, I'm tired, a little injured."

Big-serving John Isner said earlier that he wants to face a fully fit Nadal in next month's Davis Cup semi-finals.

The world number 10 said, "I'm not going to sit here and say that I don't want him to play. Everyone wants him to be healthy. Honestly, if it was up to me, I would want him to play. I would want Spain to send out their absolute best team,"