New York, NY, USA, 30 August 2016 | Darren Walton/AAP

Saturated in sweat, Australian wildcard James Duckworth posed for selfies with rapturous fans after posting the biggest win of his career at the US Open in New York.

Defying sapping heat and humidity, Duckworth rallied from a set and a service break down to defeat experienced Dutchman Robin Haase 4-6 7-5 6-3 4-6 6-3 at Flushing Meadows on Monday night.

Duckworth was unable to gain direct entry to the tournament after elbow and wrist injuries wiped out four months of his 2016 season and sent the Sydneysider spiralling to 195th in the rankings.

But he played brilliantly at times and wowed spectators – including Davis Cup captain Lleyton Hewitt – with his athleticism and Boris Becker-like dive volleys at the net.

His only stumble after turning the match around came when he twice double-faulted, blaming the floodlights, to hand Haase the fourth set.

But he regrouped after a bathroom break to charge through the deciding set and eliminate the world No.64 in three hours and 31 minutes.

“It’s nice to be back playing main draw of a Grand Slam and to be in the second round,” Duckworth said.

“I was able to fight my way through and dig deep and I’m really happy. It’s great to win.”

The 24-year-old’s reward for his breakthrough first win at the season’s final grand slam is a shot at French ninth seed Jo-Wilfried Tsonga.

“I’m looking forward to it,” Duckworth said.

“Tsonga’s a great player: a big serve, big forehand, a tremendous athlete. He’s gone deep in slams before.

“It’s a tough ask but I’m going to have to play aggressive and look to control the controllables. I’ll have to try and serve well and take it to him.”