It was a fruitful day for Australia’s male competitors at the US Open with a trio of players powering into the second round at Flushing Meadows.

Alex de Minaur is safely through following a straight-sets win over Slovakian Andrej Martin.

The Australian No.1 was too classy in all departments for Martin, and chiefly too fast around the court as he sped to a 6-4 6-3 7-5 victory in just over two hours on Wednesday.

Contesting his first grand-slam match since reaching the fourth round in New York last year, de Minaur displayed no signs of competitive rust.

He broke Martin’s serve seven times, often with clean return winners using his sizzling speed of foot to change the point of direction, and was broken only twice.

Australia’s 21st seed next faces Richard Gasquet on Friday after the veteran Frenchman eliminated 41-year-old Croatian Ivo Karlovic 7-6 (7-0) 7-6 (7-4) 6-3 in his opener.

Meanwhile, Chris O’Connell continued his extraordinary rise to prominence with a fighting four-set first-round win at the US Open.

O’Connell is through to the second round after a 4-6 6-4 7-6 (7-2) 6-4 win over Serbian Laslo Djere on his Flushing Meadows debut.

The 26-year-old’s reward, apart from a $A136,000 pay day, is a possible shot at Russian third seed and 2019 runner-up Daniil Medvedev on Friday for a place in the last 32.

O’Connell soared from outside the world’s top 1000 to the cusp of the top 100 after reaching 14 finals on the ITF Futures and Challenger tours last year, collecting five titles.

After a career dogged by injury, he had been cleaning boats on Sydney’s Pittwater Harbour to make ends meet before chalking up an unrivalled 82 match wins for the 2019 season.

As a wildcard, O’Connell showcased his grand-slam potential at the Australian Open in January, where he pushed world No.15 Andrey Rublev to four sets.

Not even the five-month suspension of the world tennis tours due to COVID-19 has been able to stall his momentum.

Ranked 35 spots below Djere, O’Connell dropped the opening set on his Open debut before mounting a spirited comeback.

The world No.116 trailed by a service break in the third set but, undeterred, eventually wore down the Serb to prevail in a three-hour, nine-minute physical battle on Court 8.

The life-changing victory has already doubled O’Connell’s 2020 on-court earnings.

John Millman is the fourth Australian through to the US Open second round after upsetting Georgia’s No.22 seed Nikoloz Basilashvili in straight sets.

John Millman’s double-handed backhand on show against Nikoloz Basilashvili. Photo: Getty

A quarter-finalist two years ago, Millman’s 6-1 6-4 6-4 victory on Wednesday has opened up his draw for another possible deep run in New York.

He joins O’Connell, de Minaur and Jordan Thompson, who won his opener on day one.

Elsewhere, former champion Andy Murray produced an astonishing fightback to outlast Japan’s Yoshihito Nishioka to advance to the second round of the US Open on Tuesday.

In his long-awaited return to grand slam singles action, the former world No.1 had to call on all of his reserves before winning 4-6 4-6 7-6 (7-5) 7-6 (7-4) 6-4.

The 33-year-old Briton, contesting a singles match at a major for the first time since the 2019 Australian Open, appeared to be heading for an early exit as a fearless Nishioka outplayed him for two sets at a virtually empty Arthur Ashe Stadium.

Yet as he has so often done in his career Murray simply refused to accept defeat.

Williams begins quest for elusive 24th slam

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Serena Williams has kicked off her latest quest for an elusive 24th grand slam singles title with a straight-sets win over compatriot Kristie Ahn in the first round of the US Open.

Williams needed just under one-and-a-half hours to come through 7-5 6-3 despite falling a break down to her world No.96 opponent in both sets.

Four straight games turned the second set on its head and enabled Williams to belatedly find the momentum she required to claim victory.

Showing early signs of nerves, the former world No.1 then found another gear to fire off 13 aces and 28 winners.

A final serve forced Ahn into an error, handing Williams her 102nd US Open match victory, as she scored her first straight-sets win since the sport was put on a coronavirus hiatus.

“I was really happy with how I just fought for every point,” Williams said in an on-court interview after the match.

She had to regain her focus, she added, and “just be Serena and close it out.”

Spain’s Garbine Muguruza, looking determined to overcome her US Open jinx, beat Japan’s Nao Hibino to collect a snappy 6-4 6-4 first round win.

Flushing Meadows has not been a happy hunting ground for the former French Open and Wimbledon champion, who this year nearly added to her collection of grand slam trophies by reaching the final in Australia.

In stark contrast to her success at the other slams, Muguruza has struggled to make an impact on the New York hardcourts.

She has made it past the second round just once in seven previous visits to Flushing Meadows.

“I was anxious a little bit because I did not play in the last six months and did not have a chance to play before the US Open to get ready for here,” said Muguruza.

“I am happy with my performance I was expecting a tough match and it was.”

Australian Open champion Sofia Kenin produced a dominant display to dispatch Belgian Yanina Wickmayer 6-2 6-2.

American Kenin, who has lifted two titles in 2020 including her maiden grand slam triumph in Melbourne, broke her opponent in the first game to set the tone for the match before claiming the opening set in just 37 minutes.

The 21-year-old started the second set just like the first to take an early lead and went on to serve out the match in clinical fashion.

“I knew I could dominate her,” Kenin said. “Today I felt like I couldn’t miss a ball. I played really good tennis and I’m proud of myself.”

No.7 seed Madison Keys needed just 55 minutes to beat Timea Babos 6-1 6-1 as the 2017 finalist looks to claim her elusive first grand slam title.

The hard-hitting American won 92 per cent of her first serve points and never faced a break point while playing smothering defence against the overmatched Hungarian.

In an all-British affair, Johanna Konta shrugged off some early resistance before overpowering Heather Watson 7-6 (9-7) 6-1.

-with AAP