Roger Federer’s respect for his next Australian Open opponent John Millman is enough to bring the Swiss great back to earth after his second round masterclass.

Federer was unstoppable in his round two match against Serbian Filip Krajinovic, taking just over an hour and a half to nail a 6-1 6-4 6-1 victory.

The third seed barely put a foot wrong with the Rod Laver crowd with commentators also in raptures after a performance that included 42 winners.

But attention quickly turned to Federer’s match-up with Millman, who also had a straight sets second round win over Poland’s Hubert Hurkacz.

The Australian famously ousted the 20-time major champion in the the round of 16 at the 2018 US Open, winning in four sets 3-6 7-5 7-6 (9-7) 7-6 (7-3).

The result is one Federer hasn’t forgotten.

“I almost passed out when I played out against him in New York,” the 38-year-old said.

“It was so hot but he had no problem as he’s from Queensland, so he was like normal stuff.”

The pair have met a two other times while Federer has got the result, they have always been tight affairs.

Federer said he had practised a lot with world No.47 Millman and rated him as one of the fittest players on the tour.

“He’s a super good guy and an unbelievably tough opponent,” he said.

“There’s not many guys fitter than him out there and those are the guys I respect the most, actually, because he gets the most out of the game.”