Roger Federer’s legendary former coach Tony Roche is at the busy National Tennis Centre practice courts, chatting about a player he calls “the ultimate professional’’.

Yet a description that undeniably applies to Federer is instead being used for the Swiss’ third-round opponent, John Millman.

Or Johnny, as Roche and others refer to the proudest of Queenslanders and nicest of guys.

Millman is the relatable everyman of Australian tennis.

The battler (not a term he is fond of) who endured injury and disappointment before carving out a fine career. The trier who is also more than that.

He calls himself a “typical Aussie bloke’’ and “one of the people’’.

Others see someone who has never forgotten where has come from, or what it was like there, even if the highlight of the 30-year-old’s career so far was reached on the world’s biggest court, Arthur Ashe Stadium, against the sport’s wealthiest and most famous name.

“He’s an example to the mortals, of which I was one, of how do you manage to hang in long enough, and then find a way, like John has, to break through,’’ said Australian tennis identity Paul McNamee.

“And then to beat arguably the best player in history I think will go down as his crowning glory.’’

Australian John Millman hopes ‘lightning can strike twice’ when he plays Roger Federer on Friday. Photo: AAP

Not that he is finished yet, but nothing since has topped that sweltering September night at Flushing Meadows in 2018, before a celebrity-studded audience – who, to be frank, were in Queens to watch King Roger, rather than the only Australian to beat him in a grand slam match this century.

It may be a slight exaggeration to suggest it belongs in the you’ll-remember-where-you-were-when-it-happened catalogue of big events, but it was also a such an irresistible occasion for Australian tennis that you’d be forgiven if you did.

Back here in Melbourne, the viewing experience was sharing the couch with a sick teenager who is also a crazy sports fan, and one horrified to discover that her mother was not, for once, cheering for Fed.

Soon enough, though, she had also taken Millman’s side as the almost-unthinkable occurred a hemisphere away.

McNamee, the former Australian Open tournament director and doubles great, was in New York that night, for an achievement he rates alongside a young Nick Kyrgios upsetting world No.1 Rafael Nadal in the 2016 quarter-finals on Wimbledon’s centre court.

Roger Federer has been in blistering form this tournament. Photo: Getty

Yes, it was debilitatingly hot and humid, Federer having stressed that he had never felt worse physically, while Millman, well, “he had no problem – he’s from Queensland’’.

But McNamee emphasises that it is one thing to be in a position to cause such a boilover, and far tougher to ultimately do so.

Especially in a situation like that one. Particularly against an all-time great of the game.

Are you worthy? Are you good enough? Can you? Really?

“That’s why I highly rate what John did in New York. Even though it was clear Roger had mid-match discomfort with the heat, you’ve still got to get the job done,’’ McNamee said.

John will leave everything out there again, but Roger’s going to be really ready for him this time.’’

Millman smiles that a consequence of 2018 was that he has spoken a lot more about the mighty Federer than he ever expected and admitted this week that the cherished experience was one of the career snapshots he will carry into retirement, eventually.

For now, he is promising “that I’ll go out there and give it a crack. Regardless of the score at the end of the day, I’ll go out there and leave it all out there. If lightning strikes twice, I wouldn’t say no to it.’’

So back to Roche, the guru who recently received the inaugural ATP Coaching Award for his contribution over many decades.

In his quiet way, the 74-year-old predicted the warrior who is no Johnny-come-lately would not be going anywhere without the bravest of fights.

“Johnny’s getting the maximum out of his game and that’s what you look for in players,’’ said Roche, who helps mentor Millman in his Davis Cup capacity and is never less than appreciative of what the leadership and example he sees.

“Johnny’s just the ultimate team man, and that’s what has been great in Australia’s culture is to have people like Johnny.

“Everybody works hard, but I think you admire people like Johnny, who’s been through some tough times and he’s coming through. He’s getting the results he deserves.’’

The sport, of course, has been blessed to have Federer for these past few decades and 20 major titles, his collaboration with Roche lasting from 2005 to mid-2007.

Tony Roche says John Millman is the ‘ultimate team man’. Photo: AAP

As to whether Roche thought back then that Federer would still be playing into his 39th year: “Oh, look, the way that he plays and the way he looks after his body, it doesn’t surprise me that he’s playing as well as he’s ever played. It’s amazing, yeah.’’

Millman will need to do everything well to beat him for a second time out of four, and is hoping for heavy conditions, and the planets to align.

Millmania had its origins north of the Tweed, but Melbourne Park is itching to experience its next outbreak.

Millman is a home favourite; Federer a darling everywhere.

Rod Laver Arena will be the venue, despite Millman’s pre-match suggestions that he might request the more raucous Melbourne Arena “but I don’t think Roger knows what that court looks like”.

He knows plenty else, though, even if he comes in with less lead-up competition than previously, and would prefer to be undercooked than overdone.

But therein lies Roche’s hope: That Federer may be slightly short of matchplay, whereas the Australian workhorse’s competitive diet has been just right.

In Federer’s words, Millman is “fit like a fiddle”; in his own, the Australian needs to make the match as physical as possible, having enjoyed a recovery day after consecutive best-of-five matches, and prepared as, well, professionally, as he always does.

“You’ve got to hope Roger’s off – and he is sometimes,’’ says McNamee.

“But he’s playing incredibly well right now, so I think it’s going to be a big ask.’’