Alexei Popyrin is refusing to let his mind wander after marching ominously ever closer to a blockbuster US Open showdown with defending champion Novak Djokovic.

Popyrin lived up to his star billing to lead four Australians into the second round on day one at Flushing Meadows.

The recently crowned Montreal Masters champion cruised past Soonwoo Kwon without even hitting top gear, eventually progressing with a 7-5 6-2 6-3 win in a tick over two hours.

Popyrin was joined in round two by fan favourite Rinky Hijikata, exciting teenage prospect Maya Joint and 2022 women’s quarter-finalist Ajla Tomljanovic.

Seeded for the first time at a grand slam, Popyrin crunched 14 aces and broke the South Korean six times while only dropping his own serve once all match.

Victory edged the 25-year-old to within one win of a likely third-round Saturday-night showstopper with the history-chasing Djokovic.

Popyrin next faces unseeded Spaniard Pedro Martinez on Wednesday (Thursday AEST).

Chasing an unprecedented 25th singles major, Djokovic will meet fellow Serb Laslo Djere after opening his campaign with a typically clinical 6-2 6-2 6-4 win over Moldovan qualifier Radu Albot in Monday night’s late match.

“I feel like I’ve had a lot of scenarios in my career where I had one more match, and then I would play a big match, so I’ve kind of gotten used to focusing on the match that I’ve got in hand,” Popyrin said.

“And then if I win that, then, yeah, obviously I’ve got Novak in the third.

“But, honestly, I’m just thinking of this match and not thinking about Novak.”

The 28th-seeded Popyrin and 18-year-old Joint led the way as Australia’s bumper 20-strong contingent made a flying start to the final tennis major of the year.

Bidding to back up his electrifying run to the fourth round last year as a wildcard, Hijikata fended off multiple set points in the first set against Alejandro Davidovich Fokina en route to a spirited 7-6 (7-1) 3-6 6-4 6-3 win over the Spaniard.

The much-hyped Joint didn’t disappoint on her grand slam main-draw debut, seeing off experienced German Laura Siegemund 6-4 7-5 to secure a career-high ranking on the cusp of the world’s top 100.

The rising star let a 5-0 lead and one match point slip in the second set before clinching the biggest win of her fledgling career.

Win or lose next up against 14th seed Madison Keys, Joint will leave Flushing Meadows tantalisingly close to the rankings cut-off mark for Australian Open direct entry.

And two years after ending Serena Williams’ storied career on Arthur Ashe Stadium, Tomljanovic drew on those cherished memories to also advance with a 6-4 6-4 win over American qualifier Ann Li.

But Kim Birrell bowed out with a 6-4 6-4 loss to Paris Olympics silver medallist Donna Vekic, the 24th seed.

One of a record five Australian women’s qualifiers, Priscilla Hon’s fine run came to an end with a 6-3 6-2 defeat to world No.2 Aryna Sabalenka, the two-time defending Australian Open champion.

And Adam Walton was unable to follow Popyrin and Hijikata into the men’s second round, succumbing 3-6 7-6 (9-7) 6-3 6-4 to French wildcard Alexandre Muller.

Another 13 Australians play on day two, including 10th seed Alex de Minaur opening his campaign against American Marcos Giron.

HOW THE AUSSIES FARED ON DAY ONE OF THE US OPEN (PREFIX DENOTES SEEDING):

Men’s singles, first round

28-Alexei Popyrin bt Soonwoo Kwon (KOR) 7-5 6-2 6-3

Rinky Hijikata bt Alejandro Davidovich Fokina (ESP) 7-6 (7-1) 3-6 6-4 6-3

Adam Walton lost to Alexandre Muller (FRA) 3-6 7-6 (9-7) 6-3 6-4

Women’s singles, first round

Ajla Tomljanovic bt Ann Li (USA) 6-4 6-4

Maya Joint bt Laura Siegemund (GER) 6-4 7-5

Kim Birrell lost to 24-Donna Vekic (CRO) 6-4 6-4

Priscilla Hon lost to 2-Aryna Sabalenka (BLR) 6-3 6-3