It seems that even superstars of sport are not impervious to the William and Kate effect. For Roger Federer, winner of a record 16 grand slams, has said that seeing Will and Kate in the Royal Box on Wimbledon Centre Court helped inspire him to victory yesterday.

I know. Is there anything they can't do?

Federer, the six-time champion at the All England Club, comfortably defeated Russia's Mikhail Youzhny 6-1, 6-2, 6-2 to set-up a semi-final with world number one Novak Djokovic.

"I really actually do enjoy seeing legends coming out, following today's tennis. Royals coming out, it's inspiring, too, in some ways, believe it or not," Federer said. "It's great for Wimbledon. It's great for the players. It's just nice to see that the Royal Box is always full. It's never empty for us. And if it is, you know they're going to come back, they're not here just to drink champagne and tea in the back. They really do come for the tennis. We feel that on Centre Court, and I do feel that. That's probably one of the reasons why I play well on Centre Court."

He added:  "I met Kate for the first time. William I've met again after Australia. They were very nice, very friendly," said Federer, "We had a bit of a chat. What exactly, it's not so important I don't think. But it was a nice conversation."

When asked if he could see himself one day joining the ranks of legends like Andre Agassi and Rod Laver, who were also in the Royal Box yesterday, Federer said: "I don't know. First I'll have to get an invitation and then we'll see."