Federer landed on his still-fragile left knee, which in February had required him to have surgery for the first time in his career, keeping him out for more than two months. Though he got up slowly at Wimbledon and finished the match, he did not finish the season. He even missed the Summer Olympics in Rio de Janeiro, which had long been one of his major late-career targets.

While his longtime rivals Andy Murray and Novak Djokovic duked it out for the No. 1 ranking and his Swiss countryman Stan Wawrinka won the United States Open, Federer got a taste of retirement with his longest break from the tour since he turned professional in 1998. Now, he will try his hand at a staple of modern tennis: the comeback. And he will do so with a world ranking of No. 16, his lowest since 2001.

“It actually felt like I had my first real comeback in April when I came back in Monaco, especially having had surgery, because I never had surgery before,” Federer said. “So that felt like a real comeback to me, but this one feels bigger, obviously, because two months is not like six months. Clearly this comeback is going to have a different place in my career, for sure.”

Federer, 35, has little left to prove. He has already won a record 17 Grand Slam singles titles and 71 lesser titles. He has maintained a standard of excellence for far longer than most tennis champions do. Although he said he had treasured his time away from the tour with his wife, Mirka, and their four young children, he insisted that no consideration had been given to making the break permanent.

“Mirka is totally committed, totally happy,” he said. “The kids love it, and I’m still hungry, and now I’m even refreshed and rejuvenated.”