Stefanos Tsitsipas insisted he played by the rules after the world number three was criticised by Andy Murray for his lengthy bathroom breaks during Monday's thrilling US Open showdown.

Murray was scathing post-match in New York, the three-time grand slam champion livid as he told reporters he "lost respect" for Tsitsipas over his controversial breaks during the Greek star's dramatic 2-6 7-6 (9-7) 3-6 6-3 6-4 first-round victory after almost five hours on Arthur Ashe Stadium.

Former world number one Murray – whose career has been devastated by injuries, the 34-year-old underwent hip resurfacing in 2019 but he has continued to be plagued by fitness problems – turned back the clock at Flushing Meadows but was unable to complete a stunning first-round triumph.

Murray was fuming after Tsitsipas took a controversial bathroom break heading into the decisive fifth set of the marathon match, spending around eight minutes off court, while the French Open runner-up also required a medical timeout for an apparent foot problem after losing the third set.

Asked about Murray's comments, Tsitsipas said during a news conference: "If there's something that he has to tell me, we should speak the two of us to kind of understand what went wrong.

"I don't think I broke any rules. I played by the guidelines, how everything is. Yeah, definitely something for both of us to kind of chat about and make sure. I don't know how my opponent feels when I'm out there playing the match. It's not really my priority.

"As far as I'm playing by the rules and sticking to what the ATP says is fair, then the rest is fine. I have nothing against him. Absolutely nothing."

With the win over the Brit, Tsitsipas became the 10th active player to defeat all four members of the 'Big Four' – Murray, Novak Djokovic, Rafael Nadal and Roger Federer.

On the length of his bathroom breaks, Tsitsipas – who celebrated an ATP Tour-leading 49th victory of the year – added: "I think it's clear that I took my clothes with me when I left the court. That's the amount of time it takes for me to change my clothes and to walk back to the court takes a little bit of time.

"I don't know what's the rule regarding that, if there is one. But as far as I know you're allowed to have two toilet breaks to go change your clothes in a five-setter, and one in a three-setter. I followed that throughout my entire career. I've never broken any rules, so I see no reason that that's a problem anyways."

It comes after controversy at the Western & Southern Open in Cincinnati, where Tsitsipas was accused of cheating by Alexander Zverev following a lengthy bathroom break after the first set of the semi-final.

Zverev told the chair umpire he believed Tsitsipas was receiving improper coaching via his cell phone.

"He took his bag with his phone and everything in it," Zverev said on the court. "This was the same thing in Paris and is going to be the same thing every other tournament he's playing."

When asked about Zverev's accusations after booking a clash with Adrian Mannarino, Tsitsipas said: "I have never in my career done that. I don't know what kind of imagination it takes to go to that point.

"That's not something I want to take seriously because it's absolutely ridiculous to be thinking about that. Anyway, that's it."