Australian wildcard Alexei Popyrin has claimed the biggest win of his career, sending world number 9 Taylor Fritz packing at the Australian Open.

The Australian, ranked 113 in the world, played to his potential and not his ranking as he put on a serving clinic to dismiss Fritz  6-7, 7-6, 6-4, 6-7, 6-2 in front of a raucous crowd on John Cain Arena.

As the crowd serenaded him with chants of "Poppy", an emotional Popyrin, who won just five matches on the main tour in an awful 2022, said this win meant the world to him.

"You guys were just incredible. Oh my God, this is crazy," Popyrin said.

"This win means so much to me.

"I won as many matches this year as I did the whole of last year and it's only January.

"This is a dream for me and I don't want to wake up at all."

The win marks the latest upset for Popyrin, who holds victories over some of the sport's biggest stars including Dominic Thiem and Grigor Dimitrov.

The victory over Fritz, who is one of tennis' fastest-rising stars, is among the best of them.

Fritz at times complained about the more vocal elements of the crowd and also received an injury timeout for treatment to his right leg after pulling up short while moving to a backhand.

But while the American's leg seemed to recover, his game did not.

Fritz took more than three hours to get a break point on the Popyrin serve, but when he did the American took his chance and took a 5-4 lead in the fourth set.

He could not finish though. A loose game and some brilliant returning from Popyrin saw the Australian break straight back.

It was not long before the pair were off to another tiebreak and, though Fritz got the early mini-break, Popyrin fought back and had match point at 6-5.

A big Fritz serve/forehand combo put an end to that before he almost bored Popyrin into a backhand error when he had set point at 7-6.

Fritz was buoyed by that and came out swinging in the final set, forcing Popyrin to save a break point in the opening game with an ace, but from there it was all Popyrin.

The Australian broke Fritz with ease for a 3-1 lead and remained untroubled on his own serve.

But he didn't need it, breaking Fritz for a five-set victory with a massive forehand.