• Roger Federer

Roger Federer (Photo : CameraSport via Getty Images)

Severin Luthi revealed that Roger Federer has already started rehabbing his re-injured knee, but the Swiss coach admitted back injury was also a factor in Federer's decision to skip the remainder of the season.

Federer stunned the tennis world after announcing he will not play at the 2016 Rio Olympics and will skip the remainder of the season after re-injuring his surgically-repaired knee at Wimbledon.

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But just a few days after the shocking announcement, Federer's coach Severin Luthi revealed the Swiss Maestro is already rehabbing his knee, although the 40-year-old Swiss admitted a back problem may have also contributed to Federer's decision to be sidelined.

"He is working with the physio ... This means he is rebuilding the whole muscle structure, the back and the leg ... If he had to play tennis today, he could do that also. The question is at what level and with what price," Luthi told Tages-Anzeiger via Tennis Magazine.  

"No, it has nothing to do with this fall. There he had a moment of being afraid, because he did not know what had happened and because he was not fully fit. Till now, he has had few experiences with injuries. I could be wrong. But for me, in retrospect, the back also has something to do with the knee."

There were speculations over Federer retiring from the sport following his latest setback that prevented him to compete at the Olympic Games and the remaining Grand Slam event in New York. But according Federer's agent Tony Godsick, the 17-time Grand Slam winner's decision to be inactive for the rest of the season only shows Federer isn't ready to call it quits yet.

"There is no gloom and doom in our camp," Godsick said, reports ESPN. "The decision was unfortunate, on the face, a bummer, but it was encouraging, too. It shows he still wants to get out there and give it a few more years."

Federer has never recovered from his losing slump, which began at the start of the season. He was plagued by injuries and setbacks, halting his pursuit for another Grand Slam title to add to his all-time record.

The unexpected decision from Federer should give him enough time to recuperate from injuries and regain the much-needed composure. And with Federer fully-intends to come back stronger and better, his return to tennis action is something fans would surely anticipate.

"The love I have for tennis, the competition, tournaments and of course you, the fans remains intact," Federer wrote in a Facebook post. "I am as motivated as ever and plan to put all my energy towards coming back strong, healthy and in shape to play attacking tennis in 2017."