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He's through to the semifinals, where he'll play his world No. 1 Rafael Nadal on Friday (3:30 a.m. eastern time on ESPN).
After failing to reach the semifinals in three of four Grand Slams last year and falling to No. 6 in the world, Federer made a dramatic switch - abandoning his old-school racket in favor of a larger model used by every top player in the sport.
Federer is using a 98-square-inch racket in Melbourne. It's a departure from the 90-square-inch model he had previously used, which stopped being state of the art 10 years ago.
According to the New York Times, Federer asked Wilson to make prototypes of a larger racket for him to test out last summer. After a period of trial and error in which Federer continued to play with (and lose with) his tiny racket, Roger finally found a model he liked last month.
Wilson made 12 of them. According to the NYT, they were handled like valuable rubies:
"Wilson, [Federer's agent] said, made 12 of that model to start with. Six ended up at his house near Cleveland, and he transported them [the Melbourne] via Los Angeles and Sydney. He showed a picture Thursday of the rackets at baggage claim, his precious carry-on luggage, which he stored mostly in nearby empty seats."
A larger racket has a larger sweet spot, giving the player a higher margin for error.
Federer said in a post-match press conference that the racket is giving him more power on the serve, and probably helping his return:
Q. One of the TV commentators was saying that the new racquet was helping you for certain shots, like the return. Do you agree?
ROGER FEDERER: Yeah, I mean, I think so. I did return really well tonight. I had good timing. I was also reading the serve well, not like other times.
Last year I had a really tough time in slower conditions against Jo. Just couldn't get my racquet on it. Probably I was maybe overall feeling bad. I don't know.
But tonight things were just clicking. It was smooth for me. I do believe I have easier power with the racquet on the serve. It might help me on the return, as well. I hope it is the case.
I still need to put many more matches and hours on it, but so far so good. It's a great start to the season with the racquet, with my body. Everything is going really well. I'm very happy.
There are other factors contributing to Federer's comeback. For one, the back injury that slowed him down last summer hasn't been an issue.
But right now the margin of between winning and losing at the top of men's tennis is so small that any slight advantage will have a dramatic effect.