From sleeping on airport floors to beating Federer: How John Millman made history.

He is the first Australian to beat Roger Federer at a major this century, but to many, John Millman is an unknown name.

On Tuesday morning, the 29-year-old Queenslander and world No 55 defeated the world No 2 Federer at the US Open, bringing ‘The Mailman’ unprecedented overnight success.

Tennis great John McEnroe even labelled the defeat as “one of the greatest upsets in tennis history”.

Set to take on his next opponent Novak Djokovic later this week, another win from Millman could land him the position as Australia’s top men’s tennis player, overtaking Nick Krygios.

But it has not been an easy feat for Millman.

Millman, who began playing tennis at age four, began playing as his four sisters all played the game.

Beginning his professional tennis career in 2008, Millman began his career competing in entry-level tournaments.

According to the Daily Telegraph, between 2007 and 2010, Millman’s world ranking quickly rose from 1461 to 204.

A post shared by John Millman (@johnnyhm) on Jul 2, 2018 at 2:51pm PDT

But times were tough and the right-hander was often strapped for cash as he tried to climb the tennis ranks.

Writing in Player’s Voice, the 29-year-old recalled “sleeping on floors of train stations and airports and literally playing just so you can afford to get a flight out of wherever you were”.

Along the way, he’s also struggled with a series of near career-ending injuries affecting his shoulder, back, hip and groin.

By April 2014, after nearly a year off the sport due to a surgery to resolve a shoulder injury, Millman was ranked as low as 1,193 in the world.

At the time he even turned to a normal day job, working at a Brisbane mortgage firm to make ends meet while unable to compete.

“One of my mates, David Laverty, who first hit with me when I was 15 years old, is very successful in the business world,” Millman recalled.

@He could see that I was really struggling. And I was. It was really tough. There’s so much doubt in your head.”

Traditional pre slam hit with @tarodaniel here in Melbourne. ???????? ???????? #australianopen #AO @tecnifibre @lottosport @highsierra_ausnz @instinct_sports

A post shared by John Millman (@johnnyhm) on Jan 13, 2018 at 8:46pm PST

After overcoming his shoulder injury, Millman went on to compete at the 2016 Rio Olympic Games, becoming the first men’s single player to win 6-0, 6-0 at an Olympic Games.

After his success at Rio, Millman lost even more time from the sport, losing the first four months of 2017 as he dealt with a groin injury.

This year, however, has been full of victories for ‘The Mailman’.

“I’m probably in a little bit of disbelief,” Millman said after beating Federer today.

“I have so much respect for Roger and everything he’s done for the game. He’s been a hero of mine and today he was definitely not at his best but I’ll take it.”

“I’m a big of John,” Federer said.

“Maybe not that many people know him, but he’s a real hard-working guy out there and those are the guys who have all the respect from us top players in the locker room. We know each other quite well, a super friendly guy, and I’m very happy for him that he’s gotten so far.”