The Swiss star and world number three, who turns 35 in August, this week plays on the Stuttgart grass for the first time as he ramps up his preparations for Wimbledon in June-July.
“It’s the grass-court season now, that’s huge for me,” said the seven-time Wimbledon champion, who headlines the Stuttgart event, which switched from clay a year ago and crowned Rafael Nadal its first champion on the new surface.
Federer made clear he had been disappointed by those who questioned – mostly on social media – the extent of the back injury that forced him out of Roland Garros.
Federer, who has been plagued by knee and back injuries this year, last missed a Grand Slam event in 1999 when he skipped the US Open.
“I was surprised to hear that some thought I pulled out because of the (Paris) weather,” said Federer, who last tasted action when he lost to Dominic Thiem in the third round in Rome nearly a month ago.
“That (rain) had nothing to do with it — either you are strong enough or you are not. I knew I made the right decision.
“After all these years, it’s Ok to miss a major. It’s not all about them anyway: it’s about health, it’s about feeling good about the rest of the season, my career and my life as well.”
Federer, one of the best tennis players of all time after racking up 17 Grand Slam titles, said he had taken the time off from Paris to get back to fitness and spend time with his family.
The 2009 French Open champion was full of praise for Novak Djokovic after his Serb rival won the Paris title for the first time at the weekend with a four-set victory over Andy Murray.
“For tennis it’s great, now he has won all of the grand slams. It’s world-class, which is rare. He did it the hard way, it was wonderful how it worked out,” Federer said.
The Swiss takes the top seeding at the hilltop Weissenhof club in Stuttgart and will await a second-round opponent after a bye.
He faces either US teenager Taylor Fritz or a qualifier.
“It will be a good week when I get on the court and play a match. A great week would be the semi-finals and a dream run would be to win,” Federer added.
“Crazier things have happened. Everything is possible this week.”