Kyrgios, 20, described the dramatic 6-7 (2-7), 7-6 (7-5), 7-6 (14-12) result against the top-seeded Swiss as superior to last year's four-set elimination of then world No.1 Rafael Nadal to reach his maiden Wimbledon quarter-final.

"I've been playing well recently on the clay, so I knew I had a good chance to go out there and do well. I stuck to my game and served well and I got the win," said Kyrgios, who saved two match points to Federer's five in the third-set tie-break, to set up a third-round appointment with American John Isner.

"I guess that's why you play the game, to play on these big courts against these big players. He's the greatest of all time, no doubt."

Federer, a four-time winner of the Madrid Open and fresh from his 85th career title in Istanbul, hailed the potency of the Kyrgios serve he lamented returning so horribly, while claiming not to be surprised by the world's No.35's performance in the big moments.

"No, because he likes the big stage. He's got nothing to lose, no fear, and he's got a great game. He can rely on his serve so much. It keeps him in the match regardless of he how he plays from the baseline," Federer said.

"All he needs to do is string a few good shots, a few good points together when it really matters. It was one of those matches. But no doubt about it, it was impressive ... He's got a wonderful serve, good potential, so I hope he keeps working hard and that he can compete for the best spots in tennis."

Yet if their styles are different, Federer concedes more common ground than just the ability to rise to an occasion.

"I think both of us probably also needed some time when we were younger to figure out our games. We have a lot of possibilities in terms of shot selection. To hit the right shot at the right time is something that for us comes a bit more difficult than a steady baseliner, who is just happy to rally. We prefer to do other things out there. That's why he might take a few more years to really crack the code for him."

If so, great strides have already been taken by the youngest man since Federer to reach two grand slam quarter-finals, and just the fifth player aged 20 or younger to have beaten both Federer and Nadal.

Kyrgios is expected to be seeded at a major for the first time at this month's French Open, where Pat Rafter in 1997 was the last Australian man to reach the semi-finals.

Davis Cup captain Wally Masur watched Kyrgios train at home on clay in Canberra before he left for Europe, where he returned from injury to reach his first ATP World Tour final last week in Estoril.

While impressed with the tall baseliner's movement on the shifting surface, Masur admits he did not expect such stellar results so early in the claycourt swing. But it is the combination of the big Kyrgios game and his big-match mentality that make virtually anything possible.

"Can Nick Kyrgios win the French Open? I'm kind of enjoying the ride at the moment," Masur said. "It's not like he's a seasoned pro who's been out there for 10 years and we kind of know what we're going to get. He's an improving, emerging player.

"The form book and rankings would suggest that winning the French would be a bit beyond him at this point, but the great thing about Nick is I'm not sure we thought last year he was going to make the quarters at Wimby, when he was down match points against [Richard] Gasquet.

"The thing about Nick when he steps out on the court is you just don't know what he's capable of, and he's still improving, so each week is one more step down that path. Look, it's very hard to put a limit on this kid's ability. I know as Australians we like to put a lid on expectations, but it's a bit hard to put a lid on Nick because he keeps bursting through."