Roger Federer should be embracing the prospect of becoming the first man to win six successive Wimbledon titles.

Instead, he finds himself locked in a desperate battle to salvage his reputation as the world's greatest player with Rafael Nadal casting an intimidating shadow over Centre Court, Federer's private playground.

When he lost his Australian Open title in January, the world number one was able to point to the debilitating effects of glandular fever.

But there was no escape clause for his humiliation at the hands of Nadal in the French Open final as the Spaniard handed him his worst career defeat.

Federer stopped the rot with a fifth title on grass at Halle to extend his winning streak on the surface to 59 matches, and he insists a return to the All England Club is the perfect antidote to his recent difficulties.

"I haven't lost on grass for six years. I still definitely feel very strong about my chances and being the big favourite going into grass," he said.

Not everyone agrees.

Australia's Pat Cash, Wimbledon champion in 1987, believes Federer has lost his aura of invincibility.

"I would hazard a guess that Nadal has burrowed himself deeper than ever into the previously rock-hard Federer self-belief," Cash told the Sunday Times.

"The way that Federer allowed his head to drop in the last set of the French Open final, when all his gambles and strategies seemed to have been ripped to shreds, suggests he has an inferiority complex that needs a lot of repair work."

Nadal has lost to Federer in the last two Wimbledon finals but came close to an upset victory in an epic five-set title match in 2007.

The Spaniard also now has his first grasscourt trophy under his belt, secured at Queen's, and boasts 11 wins against six defeats in his career meetings with Federer.

Nadal is only 22. Behind him are dangerous 21-year-olds Novak Djokovic, who took Federer's Australian Open title, and Andy Murray.

Federer has beaten Djokovic six times in eight but the last four have been shared; Murray has a 2-1 record over the Swiss.

"It's motivating to see all these young players coming up, but I'm quite confident the second half of the season is going to be better than the first," said Federer.

Should he win a sixth title, he will surpass the 1976-1980 run of Bjorn Borg.

The legendary Swede, who admitted nothing would give him greater pleasure than to see Federer clinch a sixth victory, also sees Nadal as a potential champion.

"If he survives the first two or three rounds, then I pick Nadal to win Wimbledon," said Borg.

"He's playing really good on the grass. He's feeling very comfortable."

But Federer has an ally in Andy Roddick who he beat in the 2004 and 2005 finals.

"Playing the final on red clay against Nadal is not the same as playing on a grasscourt," said Roddick.

"If anything, it's going to annoy him to where he wants to prove everybody wrong. Maybe if he wins it six times, people won't question him. People are sitting here saying, 'Can Roger win Wimbledon?' Yes, he can. He's won it five times."

AFP