Swiss master Roger Federer owns an imposing record against semi-final opponent Stan Wawrinka, but the four-time Australian Open champion cares little for such things.

Federer has defeated his Swiss compatriot 18 times in their 21 meetings, but the 35-year-old knows that won’t matter in the slightest on Rod Laver Arena on Thursday.

“Like a lot of guys, I was able to play them when they were young, which is for the head-to-head (record) an advantage,” Federer said.

“I don’t care much about head-to-heads in general because I feel like every day’s a different match up.

“I think in the beginning, he was really struggling on faster courts. You could sense in his footwork, the way he was returning, that he was uncomfortable on them.

“That’s why it was incredible for me to see that his first grand slam he was going to win was the Australian Open.”

The 2014 Australian Open title was the launching point for Wawrinka’s late career resurgence.

The 31-year-old went on to claim the French Open in 2015 and was crowned US Open champion last year.

“He’s become such a good player, I super respect that,” Federer said.

“That the guy is able to transform his game around like that, in his footwork, in his mind, also in his game plan.

“That’s his transformation and I like what I saw. He’s always been a believer that he can do it.

“It shows how far you can go.”

Federer is surprised he’s progressed so far in his search for an 18th grand slam title so soon after his return from last year’s knee injury.

“I think winning back-to-back matches in best-of-five sets against quality, great players … that’s really been for me the big question mark,” he said.

“If I could do that so early in my comeback.

“I felt I was always going to be dangerous on any given day in a match situation. But obviously as the tournament would progress, maybe I would fade away with energy, you know, that kind of stuff.

“I think now that I’m in the semis, feeling as good as I am, playing as good as I am, that’s a huge surprise to me.”