The Swiss maestro begins his first trial run with Annacone this week at the Rogers Cup, with the world No3 set to face Juan Ignacio Chela later today.
And the 16-time Grand Slam champion, who has not played a tournament since Wimbledon, believes Annacone can help him add a new dimension to his game.
“I’ve always questioned myself in the best of times and in the worst of times, even though there were not many bad moments the last seven years or so,” Federer said.
“But I always look at new ways I can improve. Paul, I think, with his experience can bring something to our team and that’s what we’re exploring right now.
“I’ve always gotten along very well with Paul, him being obviously the coach of Sampras and Henman who were sort of friends to me. So I thought it was a good time to do a test and this is our first test tournament.”
“I am happy with my fitness and form,” he added. “I have been working well in Switzerland. That is no guarantee of success but I am looking forward to getting back on tour.”
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