“The back is good, I feel fine from that standpoint,” he added.
“It’s just really the legs and the match fitness that I’m looking forward to and getting through breakers.”
Federer will play either Felix Auger Aliassime or Hubert Hurkacz in the second round of the Halle Open on Wednesday.
But he does admit to being sad that there won’t be a big crowd in attendance this week.
“I love playing here. Very little crowd is a bit of a disappointment for all of us but at the same time I’m excited to be back on the green grass and getting a win is always very nice,” Federer said.