The duo wrestled for over four and a half hours in a thrilling five-set thriller, with Tsitsipas ultimately winning 2-6 7-6 3-6 6-3 6-4 to advance to the second round at Flushing Almarai.
However, Murray was disappointed with the amount of time his opponent spent outside of court. Tsitsipas took two bathroom breaks of more than seven minutes and also took medical leave.
“It’s just frustrating because I feel like it affected the outcome of the match,” Murray said after the match. “I’m not saying I necessarily won that match, sure, but it had an impact on what was happening after those breaks.
“I rate him a lot. I think he’s a great player. I think he’s great in the game, but I don’t have time for these things at all and I’ve lost respect for him.”
Tsitsipas, who did not break any rules, took long toilet breaks at the end of the second and fourth sets and received medical time due to a foot injury before the fourth set.
Murray could have been heard complaining to Chief Referee Nico Hellworth and US Open Supervisor Jerry Armstrong about how much time Tsitsipas was taking.
The Scot said he told his team before the match to “expect” his opponent “if things don’t go his way” and revealed there had been discussions about changing the rules to prevent such long strikes.
“Finally they are [the officials] I can’t do anything because the rules are in place, Murray said. But I sit on the players council and we talk about it all the time, about changing those rules, trying to make it less easy to exploit the rules, I guess.
“Some of the suggestions are that if you take a medical timeout or a break before, let’s say, my transmission sends, you lose the game. I just started one love appointment. That’s something that’s kind of discussed. Things are, like, get a five-minute break. During a match or something – and that’s it.There are many different suggestions out there.
“That’s how I feel, but if everyone feels that’s totally cool and there’s no problem with that, I might be the unreasonable one, but I think it’s bullshit — and he knows that, too.”
Clearly, Murray was still feeling jolly despite the defeat, tweeting: “Truth of the day. It takes Stefanos Tsitsipas twice as long to go to the bathroom as it takes Jeff Buzos to travel to space. Interesting.”
After the match, Tsitsipas insisted he had done nothing wrong and that he had no hard feelings for Murray.
“If there’s something he should tell me, the two of us should talk to sort of understand what went wrong,” he told reporters. “I don’t think I broke any rules. I played according to the directions, how it goes. Yes, definitely something for both of us to talk about and make sure of.
“I don’t know how my opponent feels when I’m out there playing the match. It’s not really my priority. As much as I play by the rules and stick to what the ATP says is fair, the rest is fine. I have nothing against it. Absolutely nothing.”
Tsitsipas, who is chasing his first Grand Slam title, went on to explain why he took so much time during his bathroom breaks.
“Well, I guess I obviously took my clothes with me when I left the court,” he said. “That’s how much time it takes to change my clothes and get back to court it takes a while.
“I don’t know what the rule is about that, if there is one. But, as far as I know, you are allowed to have two toilet breaks to change your clothes in a five-set and one three-set.
“I’ve followed that throughout my career. I haven’t broken any rules, so I don’t see any reason for this problem anyway.”
Elsewhere, women’s singles defending champion Naomi Osaka made it easier in her opening match with a straight-set victory over Marie Buzkova.
In her first Grand Slam appearance since withdrawing from the French Open in June, Osaka was pressured into the first set by her Czech opponent, before closing out the match comfortably 6-4 6-1 to advance to the second round.