Federer's appearance in the California desert, where men's play begins on Thursday, marks his first tournament since falling to Nadal in Melbourne, as the 13-time Grand Slam champion nursed a nagging back injury.

Now he said he's rested and ready to bid for a fourth title in the event he won in 2004, 2005 and 2006.

"I love playing matches against him, especially those five-setters, seeing if I can hang with him physically without a problem," Federer said on Wednesday.

"He's the greatest challenger I've ever had. I am really motivated because I don't know how much better he can play," Federer added. "I don't know how much better I can play, but I am right there and he's playing the tennis of his life."

Nadal's victory in the first Grand Slam of the year marked the Spaniard's first hard court Grand Slam triumph.

He also denied Federer a record-equalling 14th Grand Slam crown. But the 27-year-old Swiss, who broke down in tears in the wake of that defeat, said he wasn't unhappy with his performance there.

"I thought I played a great match for four-and-a-half sets," he said. "I think I played great off the baseline, I just didn't serve great and I think that cost me the match also."

As the top two seeds Nadal and Federer are slated to meet in the final here, but also in the mix is defending champion and third seed Novak Djokovic of Serbia and fourth-seeded Briton Andy Murray.

Djokovic beat Nadal in the semi-finals last year, then beat surprise finalist Mardy fish in the final. Fish had shocked Federer in the semis.

Murray will be playing his first tournament since he withdrew from the quarter-finals in Dubai last month with a virus.

Federer confirmed yesterday that he hasn't arrived in California with a new coach. Australian Darren Cahill, former mentor of Andre Agassi, travelled to Federer's base in Dubai to work with him, but decided he didn't want to pursue the job.

"He said the travel was tough for him," Federer said. "He took the decision for me."

Federer said he will continue to work with Severin Luthi, Switzerland's Davis Cup captain, on a part-time basis.

"He's the Davis Cup captain and we've been working the last one and a half years together. So nothing really changes," he said. "I just continue with the great team that I have.”