Roger Federer on Thursday set-up a US Open third round clash against Nick Kyrgios who found himself at the centre of an impartiality row after an umpire climbed down from his chair to tell him: "I want to help you".
Second seed and five-time champion Federer, 37, made it 18 wins in 18 second round appearances in New York by seeing off error-plagued Frenchman Benoit Paire 7-5, 6-4, 6-4.
"I think it's always tricky against Benoit, never quite the same point. Sometimes he plays very deep in the court, then he plays up in the court," said Federer.
Also going through were Wimbledon champion and two-time US Open winner Novak Djokovic as well as Maria Sharapova, the 2006 champion in New York.
However, women's second seed Caroline Wozniacki was knocked out by Lesia Tsurenko of the Ukraine.
Kyrgios reached the third round by seeing off France's Pierre-Hugues Herbert 4-6, 7-6 (8/6), 6-3, 6-0.
The match created a huge storm after respected umpire Mohamed Lahyani lost patience with the under-performing 30th seed and climbed down from his chair to tell the Australian, trailing by a set and 3-0, to try harder.
"I want to help you," Lahyani could be heard saying. "This isn't you. I know that. You are great for tennis."
A furious Herbert said that Lahyani had over-stepped the mark.
"The umpire doesn't have to talk to him at all. The only thing he can tell him is pay attention, because if you continue like this, I'm going to give you a warning," said the 27-year-old,
"They can tell him from the chair. He doesn't need to go down. He doesn't need to say the words he said on the video. That is not his job. I don't think he's a coach, he's an umpire."
Kyrgios, however, played down the incident.
"He said he liked me. I'm not sure if that was encouragement," said the Australian who nevertheless won 19 of the last 25 games following Lahyani's unprecedented intervention.
"He just said that it's not a good look. I know what I was doing out there wasn't good."
- Two-point penalty -
US Open chiefs didn't help matters by claiming Lahyani was forced to step from his chair as the crowd noise meant that Kyrgios could not hear him.
"Lahyani was concerned that Kyrgios might need medical attention," said tournament referee Brian Earley.
"He also informed Kyrgios that if his seeming lack of interest in the match continued, that as the chair umpire, he would need to take action."
Djokovic downed Tennys Sandgren of the United States 6-1, 6-3, 6-7 (2/7), 6-2.
"I thought I played very well for the first two and a half sets and then I just lost it mentally. I got pissed off," said 2011 and 2015 champion Djokovic.
Next up for sixth seed Djokovic is Richard Gasquet of France who he has beaten 12 times in 13 meetings.
German third seed Alexander Zverev made the third round for the first time in four tries after a 6-4, 6-4, 6-2 victory over lucky loser Nicolas Mahut.
Australian Open champion Wozniacki went down 6-4, 6-2 to world number 36 Tsurenko who claimed a second top 10 win this month having also defeated Garbine Muguruza in Cincinnati.
"She played the game I should have played," said two-time runner-up Wozniacki who has endured a Grand Slam letdown since winning in Australia.
She lost in the fourth round at Roland Garros and exited in the second round at Wimbledon.
She follows top seed Simona Halep, a first round loser, out of the tournament.
Sharapova took her night time record at the tournament to 21 wins in 21 matches with a 6-2, 7-5 win over Sorana Cirstea of Romania.
The Russian, who committed 33 unforced errors, next faces 2017 French Open champion Jelena Ostapenko.
Wimbledon champion Angelique Kerber kept her bid for a second US Open title on track, outlasting Sweden's Johanna Larsson 6-2, 5-7, 6-4.
Kerber will next take on Dominika Cibulkova after the Slovakian beat Taiwan's Hsieh Su-Wei 7-6 (7/3), 4-6, 6-4 despite being docked two points for returning late from a heat break.
Belarus 26th seed Aryna Sabalenka continued her red-hot summer by seeing off 2010 runner-up Vera Zvonareva 6-3, 7-6 (9/7).
Sabalenka, who won the New Haven tournament last week and reached the semi-finals in Cincinnati, has made the third round of a Slam for the first time.