Nick Kyrgios took the opportunity to discuss the low points of his career after his victory over Daniil Medvedev, admitting he never thought he would have the chance to return to his best form.

Kyrgios conceded just one set to Medvedev in the 7-6 (13-11) 3-6 6-3 6-2 triumph at the US Open on Sunday.

It appeared during the first set tiebreaker that he was on the verge of one of his famous meltdowns, with a couple of racket slams and plenty of abuse towards his own box, but he steadied and fought back after a poor second frame.

Speaking to the media after the match, Kyrgios admitted the tiebreaker was do-or-die, saying: "I feel like if he'd got that first set, it was going to be pretty much an impossible task for me to come back and win."

This year's Wimbledon runner-up was humble and respectful when discussing the talent of Medvedev, and despite his muted celebration, highlighted what a big deal it is for him to perform well under the bright lights in New York.

"I didn't over-celebrate. It's only the fourth round, I've got quarter-finals [next]," Kyrgios said. "But it was an amazing experience obviously taking down the number one player in the world on Arthur Ashe Stadium.

"I don't really like to celebrate too much after that because I know that if I played him nine more times, he's probably getting on top of me the majority of the time.

"I hadn't won a match on Ashe before this week, now I've won two against two quality opponents, and I feel like I've been able to showcase [my talent].

"There's a lot of celebrities here, a lot of important people here watching. I wanted to get on that court and show them I am able to put my head down and play and win these big matches.

"For the tennis world I think it's important as well. People were really starting to doubt my ability to pull out matches like this at majors. I'm really proud of myself honestly because it hasn't been easy dealing with all the criticism."

Kyrgios continued to discuss how he feels he is perceived by the public and the media, saying it was more a feeling of relief than ecstasy when he finished the job.

"I feel like I'm more just proud of the way that I've bounced back after everything, honestly," he said. "I've been in some really tough situations mentally, and in some really scary places.

"Obviously if you look at it on paper, I probably wasn't expected to win that match. Maybe take a set or two if I'm lucky, give the people a show.

"It's a great win, but I come off the court and I'm just almost relieved that it's over because there's just so much pressure every time I go out on court, so much expectation, so much unpredictability of what I can do.

"I just sit there in the locker room after and I'm just super proud of the performance, because there was really a time where I didn't think I was capable of producing and doing this any more.

"I guess I'm just more relieved, and I'm super proud."