Jordan Thompson has clinched the biggest grand slam win of his career with a superb straight sets victory over No.7 seed Hubert Hurkacz at the US Open on Thursday on a bright opening to Day 4 for the Australian men playing in New York.

The 30-year-old is enjoying the finest season of his career on the regular ATP Tour and progressed to the third round of the US Open for the second time with a 7-6 (2) 6-1 7-5 victory over Hurkacz, the Polish star who ended the career of Roger Federer at Wimbledon.

He was joined in the last 32 shortly after by fellow Sydneysider Chris O’Connell, who confirmed the form line from an opening round win over 26th seed Nicolas Jarry by defeating Italian Mattia Bellucci 6-3 6-4 3-6 6-3.

The pair joined Alexei Popyrin, who will play 24-time major winner Novak Djokovic on Friday, in the third round.

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Thompson, who reached the last 16 during the Covid-19 impacted US Open in 2020, trailed Hurkacz 3-5 in the first set but rallied strongly to clinch the tiebreaker before routing the former Wimbledon semi-finalist in the second set.

Under pressure at stages on serve in the third set against the world No.7, he was able to deliver in style, with his serving down the T to the deuce court particularly effective.

Thompson, who clinched his first ATP Tour title in Mexico in February and reached the semifinals at Queens in June, missed being seeded by one ranking position but justified his reputation as a tricky opponent for the best with his triumph over Hurkacz.

His reward is a clash with 30th seed Matteo Arnaldi, a 23-year-old Italian who spent the past off-season in Melbourne leading into the Australian Open.

O’Connell, meanwhile, started the season in good fashion but struggled with a shoulder injury which forced him to withdraw from Roland Garros on the eve of the event.

He is still managing the problem but has produced his best form at Flushing Meadows, with his slice backhand proving effective on the hard courts given the surface is enhancing its skid.

Having practised with his left-handed rival earlier in the US summer, he was confident he had the game to challenge his rival and so it proved, with O’Connell winning 84 percent of the points when he landed his first serve.

The 30-year-old, who reached the third round at Wimbledon last year, will play world No.1 Jannik Sinner on Saturday in a match certain to be played on either Arthur Ashe Stadium or Louis Armstrong Stadium.

Australia’s leading man Alex de Minaur, the No.10 seed, Thanasi Kokkinakis, wildcard Tristan Schoolkate and former Wimbledon doubles champion Max Purcell are still to play their second round matches on Thursday.