Roger Federer returns from a eight-week layoff following left knee surgery Friday at the ATP and WTA Miami Open with low expectations and uncertainty over how his repaired meniscus will perform.
The 34-year-old Swiss star, winner of a record 17 Grand Slam singles titles, spent 12 days on crutches and has had only nine full training days ahead of his opener against familiar Argentine foe Juan Martin Del Potro.

"Expectations are really low, which is nice for a change. I didn't expect myself to be back here quite honestly after the surgery," Federer said Thursday. "I'm excited. I'm curious how it's going to react, how it's going to feel."

Federer, whose last Grand Slam singles crown came in 2012 at Wimbledon, also made it clear he would take no chances if something feels wrong during a match.

"If I feel something in the knee I won't play. Simple as that," he said.

Third-ranked Federer suffered the injury January 29, the morning after he lost to top-ranked Novak Djokovic in an Australian Open semi-final, as he prepared to bathe his children.

"I turned. I turned back. I felt a click in my knee," Federer said. "It was a very simple movement, one I've done a million times. I'm glad it didn't happen on a tennis court, where I could have strained it more."

Federer had an MRI exam in Switzerland, where he underwent surgery on February 3.

"I'm very happy how it went but I was very sad when I heard I had to have an operation. I thought I was going to get through my career without any," Federer said.

"It was a big shock. It was disappointing."

Rehabilitation has been advancing from crutches to walking to running and sprinting and finally full workouts.

"It's baby steps," Federer said. "I've been working really hard. It's nice to be back and show everybody that it was worthwhile to put in the work."

Federer enjoyed the time off at home, a rare pleasure this time of year.

"It was nice to be in one place, in our house, for so long," Federer said. "Then I got motivated because I saw the progress. Never had any setbacks. That was clearly crucial to why I'm here."

- Del Potro coming back too -

Federer, who as all seeds had a first-round bye, has a 15-5 career record against Del Potro, although the South American won their biggest meeting in the 2009 US Open final.

Del Potro is in only his third event of a comeback following left wrist surgery last year.

"It's very exciting. We've had some good matches over the years," Federer said of facing Del Potro first. "It's nice to see him back. I haven't seen him play at all so I don't know what to expect. We're in a similar situation but his injury was much greater. I guess I'm going to focus on my own situation."

Del Potro, ranked 366th, said of facing Federer: "I don't think it's going to be a test for me. I'm going to play my best and have fun on the court."
SourcE: AFP