Roger Federer says he is mentally and physically rejuvenated

— -- Roger Federer says a six-month absence due to a knee injury has given him a mental and physical refresh that could prolong his career.

The 35-year-old had surgery on his left knee in February and announced in July that he needed extensive rehabilitation.

"To have had this layoff, rejuvenated, refreshed ... maybe mentally I needed this rest more than I thought I would," he told reporters on a conference call, according to Reuters.

"Maybe my body needed a rest more than I thought it would. I tried to look at the big picture, I hope it's going to pay off.

"At least one thing I know now is I have no regrets. I did everything this year to get my body back in shape. It didn't feel too gruelling, too long, too hard to go through this process. I have actually enjoyed it."

Federer, the 17-times winner at Grand Slam events, will play at the Hopman Cup, in Perth, Australia, starting on Jan. 1, when he partners compatriot Belinda Bencic, 19, in preparation for the Australian Open.

He had appeared in 65 successive Grand Slams before he missed the French Open with a back problem; the last time he didn't compete at one of the four majors before that was at the 1999 US Open.

"I believe that it could be very beneficial for the future of my tennis career," Federer said of his layoff.

"This year is unique because, maybe more than any time before, I need matches at the beginning of the season."

Federer, who also reportedly called for an improved anti-doping programme in tennis once again, said he was impressed with? Andy Murray's?overtaking? Novak Djokovic?at the top of the game.

"Credit to Andy for not becoming world No.1, but finishing world No.1," he said. "Those are two separate things. Finishing a year as world No.1 -- it's a different animal."