He has not been beaten at Melbourne Park since losing to eventual champion Marat Safin in the 2005 semi-finals and the big Russian, who is now healthy after two years of injury, looms as one of his biggest threats.

The twice grand slam winner, considered by his peers to be one of the few players able to challenge Federer when on form, has been plagued with knee injuries in the past two years but said he feels healthier than he had in "many years".

"I've been suffering from my knee injury that took me quite a long time to recover," said Safin. "Now I feel pretty secure and I can wait for some results."

World number two Rafael Nadal will again be one of Federer's main rivals for the title at Melbourne Park but the enigmatic David Nalbandian's chances could have ended with a back injury he sustained while practising with Safin earlier this week.

The Argentine, who celebrated his 26th birthday last week, beat Federer and Nadal twice each late last year and has the all-court game to challenge both.

However, back spasms on Wednesday forced him off the court against Safin and doctors advised him to rest for at least four days, cutting short his preparations.

Novak Djokovic, who beat Federer in the final of the Montreal Masters before losing to the world number one in the U.S. Open final, will be looking to cement his top-three status.

Roddick said it would be interesting to see how the Serb responded to the added pressure.

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