Nick Kyrgios is staying cool despite his explosive start to the US Open setting up the prospect of another dream grand slam run.

Australian teen sensation Kyrgios lived on the edge before eliminating two-time semi-finalist and 21st seed Mikhail Youzhny 7-5 7-6 (7-4) 2-6 7-6 (7-1) in a spectacular encore to his breathtaking Wimbledon win over Rafael Nadal.

Youzhny had beaten Nadal and fellow former Open champions and world No 1s Andy Roddick and Lleyton Hewitt in past visits to Flushing Meadows and only two weeks ago stopped the giant-killing run of Jo-Wilfried Tsonga in Cincinnati.

But the world No 23 had no answer to Kyrgios's firepower as the Australian crunched 26 aces and 68 winners in the four-set demolition job.

"I knew I had to serve well. Those are good stats," Kyrgios said.

Apart from overcoming Youzhny's class and vast experience, Kyrgios defied searing heat, a nagging left-arm injury and three code violations to join fellow Australians Matt Ebden and Anastasia Rodionova in the second round.

"I was struggling a little bit about the two-and-a-half hour mark," he said.

"But I knew that if I hung in I would get that second wind where I could start playing good tennis again, and that's what happened in the fourth set."

Kyrgios also flirted with disqualification in the fourth set after being penalised a game for his third misconduct warning.

He smashed a ball out of the stadium in frustration in the second set, then dropped the F-bomb before the chair umpire issued a game penalty for another audible obscenity.

"It was just an outburst and hopefully I will be able to control that the next time I play," the 19-year-old said.

Taking out Youzhny has opened up Kyrgios's draw, with veteran world No 18 Tommy Robredo the only seed standing between the Wimbledon quarter-finalist and a place in the last 16.

Kyrgios, though, said he wasn't looking beyond his second-round tussle with Italian Andreas Seppi, another seasoned campaigner ranked 11 spots above the Australian at No 49 in the world.

"He's a quality player. It's going to be a tough match. He's solid on both wings. He has a good serve as well," Kyrgios said.

"I think I'm going to have to play aggressive and keep the match on my racquet. It's going to be exciting."

Kyrgios showed maturity to overcome the threat of disqualification and a fourth-set deficit to close out his first main-draw win in New York.

While Youzhny is no Nadal, the shot-making 32-year-old entered the match with credentials and form.

His recent success over Tsonga came the week after the Frenchman had taken down Novak Djokovic, Andy Murray, Grigor Dimitrov and Roger Federer in consecutive matches to win the Toronto Masters.

Ebden and Rodionova completed a superb three-from-three opening day for Australia.

Ebden toppled German Tobias Kamke 6-4 6-3 7-6 (7-2) to book a second-round encounter with Argentine Leonardo Mayer, while Rodionova surprised rising star Camila Giorgi 1-6 7-5 6-3 and next faces another Italian in 13th seed Sara Errani. - AAP