Nick Kyrgios has cast friendship aside to cruise into the US Open second round with a straight-sets dispatch of his grand slam-winning doubles partner Thanasi Kokkinakis.

Kyrgios broke Kokkinakis in each of the first two sets, then clinched the win in a tiebreaker to take bragging rights in the all-Australian affair 6-3 6-4 7-6 (7-4) at Arthur Ashe Stadium on Monday night.

The fuss-free victory, after Serena Williams’ drama-charged triumph in the preceding match, completed a fine opening day for Australia, with Alex de Minaur, Ajla Tomljanovic and Jordan Thompson also advancing.

Kokkinakis, John Millman – in five gruelling sets in scorching heat – and Daria Saville were the only casualties.

Kyrgios, though, was the most impressive of the four winners.

The Wimbledon finalist was untouchable on serve, not offering a single break point all match and barely giving Kokkinakis a look in on his deadly delivery.

As well as clearing one big hurdle with success over his great mate, Kyrgios also had two other danger men removed from his section of the draw.

His projected second-round opponent Ugo Humbert, the big-serving southpaw who stretched Kyrgios to five sets in a Wimbledon thriller last year, crashed to a surprise defeat to fellow Frenchman Benjamin Bonzi.

And if he beats Bonzi on Wednesday, Kyrgios won’t be facing 16th seed Roberto Bautista Agut as expected in the third round after the Spaniard slipped up against American wildcard J.J. Wolf.

Bautista Agut thrashed Kyrgios for the loss of only seven games in New York last year but his demise leaves the Canberran with a seed-free path to a possible last-16 showdown with world No.1 and defending champion Daniil Medvedev.

Kyrgios wasn’t looking forward to facing Kokkinakis and, true to his word, there were no histrionics from the combustible talent, just the odd laugh between the pair.

But certainly no donations from a focused Kyrgios, aside from perhaps one loose under-arm serve at 40-love up midway through the opening set that Kokkinakis picked off for a winner.

Kyrgios’s otherwise clinical win was the 17th from his past 20 outings as the world No.25 bids to crown his best season year on tour with a breakthrough grand slam title.

HOW THE AUSSIES FARED ON DAY ONE OF THE US OPEN:

Men’s singles, first round

18-Alex de Minaur bt Filip Krajinovic (SRB) 7-5 6-2 6-3

23-Nick Kyrgios bt Thanasi Kokkinakis 6-3 6-4 7-6 (7-4)

Jordan Thompson bt Lorenzo Sonego (ITA) 2-6 1-6 6-2 6-4 6-4

John Millman lost to Emilio Nava (USA) 7-6 (9-7) 4-6 7-6 (7-4) 1-6 6-1

Women’s singles, first round 

Ajla Tomljanovic bt Karolina Muchova (CZE) 6-3 7-6 (7-5)

Daria Saville lost to Elena-Gabriela Ruse (ROM) 3-6 6-2 6-4