World number three Stefanos Tsitsipas was defiant as his Grand Slam hopes evaporated on Friday, saying "everyone suddenly is against me" and insisted he was innocent of wrongdoing in a bitter saga over bathroom breaks at the US Open.

The Greek unwillingly assumed the role of tournament villain at Flushing Meadows when Briton Andy Murray accused him of cheating over a lengthy trip to the bathroom at a critical point in their first-round match.

The debate over toilet breaks finally closed out in dramatic fashion as 18-year-old Carlos Alcaraz handed Tsitsipas a shock defeat in five sets and the rowdy New York crowd again booed him for stepping into the locker room at a crucial point in the match.

"I took my toilet break as a normal athlete," Tsitsipas said afterward, adding that he had only changed from wet clothes to dry clothes.

"Might have taken a bit longer than other athletes. But if there is a rule that says there's a specific amount of time that you are allowed to take, then I would probably try and follow that protocol, that rule."

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Tsitsipas ended the English-language portion of this press conference on Friday by pointing the finger at other players, saying he had not complained in the past when competitors took their time in between first and second serves.

"There is not a rule for that that says how much time you have to take between two serves. But I respected it," he said. "These players that everyone knows they're taking so much time but no one says anything.

"I don't know why everyone suddenly is against me."

Former champion Sloane Stephens, who lost in the third round on Friday, also called for a rule change, saying the extended bathroom breaks were a form of "gamesmanship."