Alex de Minaur has saluted his NSW "State of Origin" cohorts after spearheading Australia's best start to a US Open in almost 30 years.
Backing up gingerly from his first match in seven weeks, de Minaur recovered from an early deficit to see off Finnish qualifier Otto Virtanen 7-5 6-1 7-6 (7-3) and warned he was "getting better every day".
Jordan Thompson also rose to the occasion to claim the biggest scalp of the tournament yet, sending world No.7 Hubert Hurkacz packing with a rollicking 7-6 (7-2) 6-1 7-5 victory to open day four at Flushing Meadows.
Chris O'Connell also progressed with a 6-3 6-4 3-6 6-3 win over Italian Mattia Bellucci to join in-form 28th seed Alexei Popyrin in the third round.
Popyrin will square off with defending champion Novak Djokovic on Friday night (9am Saturday AEST) as Australia have four men in the last 32 in New York for the first time since 1997.
"Look, I would love to have a State of Origin in the tennis. I think we would have a pretty strong team," de Minaur gloated about all four hailing from Sydney along with fellow top-100 stars James Duckworth, Max Purcell, Rinky Hijikata and Aleksandar Vukic .
"All the Sydneysiders, a lot of us, we've grown up together, hitting with each other, and it's great to see us all doing well."
The quartet are following in the footsteps of 1997 third-rounders Scott Draper, Mark Woodforde, Mark Philippoussis and eventual champion Pat Rafter.
At one stage, it seemed like the Australians were heading towards a 50-year first with six or even seven players making the last 32.
But Thanasi Kokkinakis bombed out, inspired wildcard Tristan Schoolkate failed to convert two match points and Max Purcell quit with a leg injury.
Still playing while only "80 to 85 per cent" fit, de Minaur was chuffed to advance to the third round for the sixth time in the past seven years.
The 10th seed conceded after his four-set tournament opener on Tuesday he was playing less than 100 per cent fit and without his usual movement having been sidelined since Wimbledon with a hip injury.
The 2020 Open quarter-finalist's prospects of another deep run didn't look flash when he fell behind 5-2 in the first set.
But he battled back to reel off seven straight games to take a stranglehold on the match.
"Expectations were very low going in. I wasn't really sure if I was going to be able to be here and compete so I'm taking every day as a bonus," de Minaur said.
After missing a grand-slam seeding for the first time by just one rankings spot, Thompson has taken matters into his own hands to give himself a golden opportunity to match his charge to the last 16 in 2020.
Hurkacz, famous for ending Roger Federer's storied Wimbledon career, appeared in control early, also racing to a 5-2 lead in the first set.
That's when Thompson, proudly decked out in the Australian green and gold, stepped up to fight back and secure the biggest win of his 37-slam career.
He faces Italian world No.30 Matteo Arnaldi next and could meet de Minaur in the fourth round.
O'Connell earned a show-court crack at world No.1 Jannik Sinner with his victory.
As well as a shot at the reigning Australian Open champion, O'Connell is guaranteed the biggest pay day of his career with a cheque for at least $US215,000 ($A315,000) coming his way.
But Kokkinakis suffered a disappointing let-down to bow out.
Two days after eliminating dual grand slam finalist Stefanos Tsitsipas, Kokkinakis crashed to a deflating 6-4 7-5 7-5 loss to Portuguese baseliner Nuno Borges.
Purcell was trailing American 14th seed Tommy Paul 7-5 6-0 1-0 when he couldn't go on, while Schoolkate succumbed 6-7 (4-7) 2-6 6-2 7-6 (7-5) 7-6 (10-3) to exciting Czech Jakub Mensik in a deciding match tiebreaker after a pulsating four-hour, 14-minute battle.
HOW THE AUSSIES FARED ON DAY FOUR OF THE US OPEN:
Men's singles, second round
10-Alex de Minaur bt Otto Virtanen (FIN) 7-5 6-1 7-6 (7-3)
Jordan Thompson bt 7-Hubert Hurkacz (POL) 7-6 (7-2) 6-1 7-5
Chris O'Connell bt Mattia Belluci (ITA) 6-3 6-4 3-6 6-3
Thanasi Kokkinakis lost to Nuno Borges (POR) 6-4 7-5 7-5
Max Purcell lost to 14-Tommy Paul (USA) 7-5 6-0 1-0 retired
Tristan Schoolkate lost to Jakub Mensik (CZE) 6-7 (4-7) 2-6 6-2 7-6 (7-5) 7-6 (10-3)
