Stefanos Tsitsipas was booed by the crowd on Arthur Ashe Stadium during his four sets win over Adrian Mannarino on Wednesday evening.
The Greek players went for a toilet break for more than seven minutes after losing the third set which received a negative reception from those in attendance.
It follows on from Andy Murray saying he “lost respect” for the 23-year-old for taking long breaks during their first-round clash on Monday which Tsitsipas won in five sets.
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The world number three powered his way through to the third round, slamming down 27 aces in his 6-3, 6-4, 6-7 (4), 6-0 victory over the Frenchman and the Greek insisted he is not breaking any rules.
The Grand Slam rulebook states players should take a “reasonable” amount of time for toilet breaks, but there is no set time limit.
“If I break a rule, sure, I’m guilty. I agree; I’m not doing something right,” Tsitsipas said after the match which was played with a roof on due to heavy rain from remnants of Hurricane Ida.
“If I’m staying within the guidelines, then what’s the issue?
“I haven’t done anything wrong, so I don’t understand. The people love the sport; they come to watch tennis. I have nothing against them. I love the fans. But some people don’t understand.
“That’s all. They don’t understand. They haven’t played tennis at high level to understand how much effort and how much difficult it is to do what we are doing.
Sometimes we need a short break to do what we have to do.
Mannarino said afterwards that the rule needs to change.
He said: "He's not doing anything wrong, I think the rule is wrong.”
Tsitsipas will play one of tennis’ rising stars, 18-year-old Spaniard Carlos Alcaraz, in the third round on Friday.
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