Andy Murray said he has lost respect for Stefanos Tsitsipas in a scathing criticism of the world number three's excessively long bathroom break at the US Open.

Tsitsipas rallied past three-time grand slam champion Murray 2-6 7-6 (9-7) 3-6 6-3 6-4 in a thrilling five-set battle in the opening round of the major at Flushing Meadows on Monday.

Murray's 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 – however he turned back the clock in a heroic display on Arthur Ashe Stadium, where the former world number one led two sets to one before Tsitsipas' comeback.

But the opening-day showdown was overshadowed by Tsitsipas' controversial bathroom break at the end of the fourth set – the Greek star spent around eight minutes off court, much to the frustration of Murray.

Tsitsipas also required a medical timeout for an apparent foot problem after losing the third set to 2012 champion Murray, who was far from impressed following almost five hours of action.

"It can't be a coincidence that it's happening at those moments. I don't believe it [Tsitsipas' foot] was causing him any issue at all," said world number 112 Murray after failing to progress beyond the first round of the US Open for the first time in 15 appearances.

"The match went on for another two-and-a-bit hours after that. He was fine, moving great I thought. It's just disappointing because I feel it influenced the outcome of the match. I'm not saying I necessarily win that match [without Tsitsipas' delays], for sure, but it had influence on what was happening after those breaks.

"I rate him a lot. I think he's a brilliant player. I think he's great for the game. But I have zero time for that stuff at all, and I lost respect for him."

"If people don't care enough about it to change, that's fine," Murray said of players taking long breaks.

"Look, I'll speak to my team about it. I'll listen to what, I don't know, fans, players and everything are saying about it. Maybe I'm being unreasonable. Maybe I'm overreacting to something because I lost the match.

"But yeah, right now sitting here I feel like it's nonsense and they need to make a change because it's not good for the sport, it's not good for TV, it's not good for fans. I don't think it's a good look for the players either.

"I'm sitting in here after a match like that against one of the best players in the world, and rather than talking about how fantastic he is, how good he is for the game, how great it was for me that I was able to put on a performance like that after everything that's gone on the last four years – I'm sitting in here talking about bathroom breaks and medical timeouts and delays in matches.

"That's rubbish, I don't think that that's right. I said I don't want to do press tonight because I know I'm going to sit here and it's going to seem like I'm just smashing him. Yeah, that's annoying for me because sounds like sour grapes because you've lost a match and everything.

"I would have said the same thing if I'd won, I promise. It was nonsense, and he knows it."