World No.4 Karolina Pliskova fired off eight aces to defeat American wild card Caty McNally 6-3, 6-4 in the first round of the US Open here on Tuesday, as she bids for an elusive maiden major.

Pliskova, the 2016 runner-up, said after the match: “I started really well and then lost my focus a little bit at the end of the first set. She played (at) a really good level. She has a good future.”

Belinda Bencic, seeded 11th, went past Arantxa Rus 6-4, 6-4.

In-form German Alexander Zverev extended his winning streak to 12 matches by completing a routine 6-4, 7-5, 6-2 win over local favourite Sam Querrey in less than two hours.

Murray fumes

Andy Murray was clearly angry with the lengthy bathroom breaks taken by his first-round opponent Stefanos Tsitsipas after he lost the match 6-2, 6-7 (7-9), 6-3, 3-6, 4-6 on Monday.

Murray said he had been warned by his team to be prepared for disruptions such as a bathroom break or medical timeout if his third-seeded opponent saw the match slipping away. And if that was the Greek’s plan it worked to perfection.

“I think he’s great for the game but I have zero time for that stuff at all,” said Murray, who left the court after a profanity-laced “I lost respect for him.”

Currently there are no time limit on bathroom breaks. “I don’t think I broke any rules,” Tsitsipas said.

Murray, a member of the ATP Player Council, said the issue of delay tactics comes up regularly and discussions have been held on ways to keep rules from being exploited.

“It’s nonsense. And he knows it, as well,” Murray said.

The last match of the first day didn’t get going until after 11pm and ended after 1am on Tuesday, with No. 2 seed Daniil Medvedev, a two-time major finalist, overwhelming Richard Gasquet 6-4, 6-3, 6-1.

Osaka advances

“When we didn’t have a crowd,” reigning champion Naomi Osaka said after beating Marie Bouzkova 6-4, 6-1.

“I know it felt quite lonely for me.”

That was Osaka’s first grand slam match since she pulled out of the French Open in late May for a mental health break.

A 20-year-old wild-card entry has tied the women’s US Open serve speed record of 129 mph (207.61 kmph) set by Venus Williams 14 years ago.

Alycia Parks hit that mark during a 3-6, 5-7 first-round loss to Olga Danilovic.