Nick Kyrgios says he could have gone to a “dark place” when losing the third set of his second-round match on Thursday night, but he kept his cool to secure a four-set win against Frenchman Gilles Simon.

The Australian won applause from the supportive crowd at Melbourne Arena for noting that he kept focus having raced through the first two sets.

Simon, ranked world No.61, stepped up his game in the third before Kyrgios steadied to win 6-2 6-4 4-6 7-5.

“I definitely lost my way a little bit,” Kyrgios conceded on Channel Nine after the match.

“He’s a tough competitor. He knows how to win matches. I had to refocus.

Tweet from @AustralianOpen

“I could have gone to a dark place in the fourth set. I somehow pulled it away. I mean, it was a tough match. I’m happy to get through.

That would have been very interesting if it went to a fifth set.’’

Kyrgios pulled out 28 aces – boosting his charity drive for bushfire relief – but would not entertain thoughts of how far he could go in the tournament.

“I’m not thinking ahead,” he said. “There are a lot of Aussies in the draw. A lot of great players. I’m taking it one match at a time.”

If he did care to look ahead, Kyrgios would see Rafael Nadal, who booked a straight-sets win over Argentine Federico Delbonis.

Tweet from @AustralianOpen

The world No.1 was taken to a second-set tiebreak but was otherwise untroubled in the 6-3 7-6 (7-5) 6-1 second-round victory on Rod Laver Arena.

“I lost a lot of opportunities on break points. Honestly, I found a way to finally win that second set and in the third, I think I played a little bit more relaxed,” he told Channel Nine.

Swiss star Stan Wawrinka beat Andreas Seppi in an epic five-setter to win 4-6 7-5 6-3 3-6 6-4 in three hours and 38 minutes.

“It was a tough five-setter that could have gone either way,” he said after the match. “I kept fighting and I’m super happy to get through.”

Earlier Australian wildcard Alex Bolt was the latest local to give a top seed a scare.

The world No.282 took Dominic Thiem led by two sets to one before the No.5 seed steadied to win 6-2 5-7 6-7 (7-5) 6-1 6-2.

In a match lasting three hours and 22 minutes, the South Australian left-hander was overpowered in the final two sets, but won more fans with his gutsy effort.

Tweet from @AustralianOpen

Thiem was beaten at the same stage of last year’s Open by another Australian wildcard in Alexei Popyrin.

Popyrin was the big winner on day four, setting up a clash with fourth-seeded Russian Daniil Medvedev after overpowering Spain’s Jaume Munar 6-2 7-6 6-2.

Tweet from @AustralianOpen

The pair have similar styles as well as Russian lineage, Popyrin still rising up the ranks at No.96 in the world but with a big serve and forehand and impressive movement for his height.

Medvedev breezed into the third round with a straight-sets win over qualifier Pedro Martinez.

One of the title fancies at Melbourne Park, Medvedev overpowered the Spaniard 7-5 6-1 6-3 in two hours and nine minutes.

Alexander Zverev also had a convincing second round, marching into the last 32 without dropping a set following his 7-6 (7-5) 6-4 7-5 victory over Egor Gerasimov.

Earlier on Thursday, Australian duo Ajla Tomaljanovic and Priscilla Hon bowed out in the second round of the women’s singles.

Tomaljanovic went down 6-3 3-6 6-3 to two-time major winner Garbine Muguruza from Spain, and Hon was outclassed 6-3 6-2 by another former world No.1, Angelique Kerber from Germany.

Nadal lives inside Kyrgios’s head

Is Nick Kyrgios obsessed with Rafael Nadal? You’ve got to wonder after the latest nod to their ongoing spat.

During his four-set win over Frenchman Gilles Simon, the Australian offered up his impression of Nadal’s lengthy delays when serving.

Tweet from @balrajshukla

The Kyrgios snark amused the umpire and even his opponent – who followed up with his own impression of the world No.2  – but one wonders whether Nadal will see the humour, with the pair on course for a round four showdown.

The edginess follows Nadal’s comments early last year that Kyrgios needed to show respect for the crowd, his opponent and himself.

“I’m different. Rafa’s different. He can focus on what he needs to do,” Kyrgios said at the time.

For his part Nadal wowed the crowd in his straight-sets win over Federico Delbonis with the care he showed to a ballgirl who was struck during the match.

With Kyrgios winning plaudits for his bushfire relief efforts, Nadal it seems is also no slouch in the hearts and minds department.

Tweet from @AustralianOpen

Coming up on day five …

Roger Federer (SUI) v John Millman (AUS)

Millman has been impressive in his two wins to date over Ugo Humbert and Hubert Hurkacz. But Federer was simply sublime in his second-round demolition job of Filip Krajinovic.

Stefanos Tsitsipas (GRE) v Milos Raonic (CAN)

Melbourne’s Greek diaspora will be out in force again to cheer on Tsitsipas, who is looking to match his thrilling run to the semis last year at Melbourne Park. The power-serving Raonic is also a former Open semi-finalist.

Serena Williams (USA) v Wang Qiang (CHN)

In her pursuit of a record-equalling 24th major singles title, Williams comes up against a fellow seed for the first time. The Chinese enjoyed a career-best campaign in 2019, reaching the third round or better at three of the four slams and seeing her world ranking reach as high as 12.

Ash Barty (AUS) v Elena Rybakina (KAZ)

The first Australian woman to reach the third round for four straight years at Melbourne Park, Barty remains on track to end the country’s 42-year Open singles drought. But the world No.1 faces a stern test of her title credentials against an opponent with 11 wins from 12 matches already under her belt this summer.

-with AAP