The Swiss former world No 1 is hoping he will recover in time for Friday’s first singles.
The 33-year-old had to withdraw from Sunday???s final at the O2 Arena in London after sustaining the injury in his match with Stan Wawrinka who is also part of Switzerland???s team in Lille this week.
Federer said: “It’s definitely not good enough to practice. I wish progress would be faster but we’re trying hard.??
???You know, we’re heading in that direction. I feel it’s definitely a little bit better than it was on Saturday night and Sunday and also Monday.
“I’m hopeful. Clearly I’m not going to talk exactly about what my back problem is. It’s something I’ve had in the past.”
As for training again, he added: “It’s been a slow process. I wish I could be on the practice courts but I can’t be there yet. I’m hopeful for Wednesday.”
Hosts France claim they are not following Federer’s health problems too seriously.
Jo-Wilfried Tsonga said: “The important thing for us is to stay focused on ourselves, on our team.
???What we need is to have a perfect performance. What we can do is just play tennis. Anything else is not really our business.”??