London:Three-time winner Boris Becker can't see past Roger Federer as favourite to retain his Wimbledon tennis title with a sixth straight success.
But the German says that Rafael Nadal is fast improving as a grass-court force.
"It is very tough to go against a five-time champion," the German told London's Daily Telegraph on Monday.
"Rafael Nadal has clearly improved greatly on grass, while Novak Djokovic is the third player in the group, but I feel that with the history Roger has at Wimbledon, the winning record, you don't bet against him in the same way that you don't bet against Nadal on clay."
Becker, a commentator for the BBC during the fortnight, adds that Federer's third straight Roland Garros final loss to Nadal will not have affected his legendary Wimbledon confidence.
"The manner of his defeat (he won just four games) was shocking, but I don't believe it can have affected him psychologically. He always arrives at that tournament knowing that, on clay, Nadal is a little bit better, so I don't imagine mentally he is really hurt by it.
"I think he's more motivated this year because he knows that if he doesn't win Wimbledon, his number one ranking is at stake. To be recognised as the top player at the end of the year, Federer needs to win Wimbledon. That will be very much in his mind."
Rain man not in favour of Wimbledon roof
Former Wimbledon referee and noted tennis maverick Alan Mills says the new centre court roof due to be operational at next year's edition may just be another erosion of the event's noted sense of tennis tradition.
The official called the "Rain Man" during his 23 years on the job, said he is not particularly keen on the new technology designed to beat the fickle English weather.
Mills made his name on international television over the decades with countless cutaways of him scanning the skies during moments of impending weather. Once he gave the word, crack coverers on each court would spring into action to protect the lawns.
"I personally don't like a roof being there," said the still-active official. "However, I can understand the reason for it: so 15,000 people can watch live tennis and also for television. The television revenue is very important.
"When it was decided that there was going to be a roof, I asked a lot of players and I did not find one who said it was necessary.
"They said it was all part of the predictability and the unpredictability of the game. You can play a beautiful game on the grass court with the weather good, the next day you go on you come off. It is part and parcel of Wimbledon."
Mills stepped down from his job after the 2005 edition.