Popyrin sensationally snapped Djokovic’s 18-year grand slam winning streak over Australians with a seismic 6-4 6-4 2-6 6-4 victory under the bright lights of Arthur Ashe Stadium on Friday night.

As he was at the Australian Open, French Open and Wimbledon, Djokovic had once again been desperate to break Margaret Court’s all-time record of 24 singles majors with a fifth title at Flushing Meadows.

Instead 25-year-old Popyrin can himself dream big after sending the ageing world No.2 packing to storm into the last 16 of a slam for the first time.

While Djokovic was gripped with serving yips, the ice-cool Sydneysider was rock solid on his delivery, fending off seven of eight break points he faced during a tension-marred fourth – and ultimately – deciding set.

Djokovic dropped serve five times and coughed up another extraordinary 14 double-faults to take his tournament tally to a shocking 32 in eight-and-a-bit sets including a second-round retirement from fellow Serb Laslo Djere.

Fittingly, Davis Cup captain Lleyton Hewitt was in Popyrin’s courtside box for the biggest win of the former French Open junior champion’s career.

Not since Hewitt in the US Open third round in 2006, when Djokovic was only 19, had an Australian conquered the longest-serving world No.1 in tennis history.

Since then Djokovic, who completed the so-called golden slam with elusive Olympic Games glory last month, had chalked up 15 successive victories over Aussies at the majors, including exacting revenge against Hewitt four times.

The sport’s now-undisputed GOAT had also taken down Jordan Thompson, Alex de Minaur,  Nick Kyrgios, John Millman, Carsten Ball and Thanasi Kokkinakis and Bernard Tomic twice each.

Djokovic had also denied Popyrin in four sets at both Wimbledon and the Australian Open this year.

But “not tonight”, Popyrin could have said this time when the pair shook hands at the net on tennis’s biggest stage as more than 23,000 fans digested the monumental upset.

“Third time lucky, I guess,” he said.

“Honestly, we had some battles at Australian Open and at Wimbledon.

“I had my chances of getting in those matches but didn’t take them.

“This match I was able to take my chances when I got him and play some good tennis.

“It’s unbelievable because I’ve been in the third round about 15 times but I haven’t been able to get past to the fourth round in my career.

“And to be able to do it against the greatest of all time, to get in to the fourth round is unbelievable.”

Popyrin entered the Open seeded at a slam for the first time after also becoming the first Australian since Hewitt in 2003 to win an ATP 1000 crown.

But few could have predicted the clinical manner in which the Montreal Masters champ dismantled Djokovic.

In a huge turning point, Popyrin held serve from 0-40 in the sixth game of the opening set before breaking Djokovic at 4-4 and closing out the set to love.

The gritty underdog shrugged off the disappointment of not nabbing another break in the first game of the second set when Djokovic dished out three double-faults.

Popyrin patiently waited for another chance, and took it with a sizzling forehand pass to break for 5-3 and then seize a commanding two-sets-to-love advantage.

Djokovic had battled back from two sets down eight previous times in his unparalleled career and threatened to once more after taking the third in champion’s style.

But there was no ninth life for this tennis super Novak when Popyrin refused to blink under the intense pressure and cashed in on five double-faults from Djokovic in one decisive game.

In a consolation, Djokovic’s next chance to surpass Court’s grand slam tally will come at Melbourne Park in January at the Australian.

But the 10-time champion will be four months shy of 38 by then.