NEW YORK — Jannik Sinner never gave Christopher O'Connell, his third-round opponent at the US Open on Saturday, even a moment to contemplate pulling off the sort of monumental upset that eliminated Novak Djokovic and Carlos Alcaraz.

"It shows that this sport is unpredictable. Whenever you drop a little bit of your level — if it's mental, if it's tennis-wise or physical — at the end, it has a huge impact on the result," Sinner said. "Both opponents who they lost against, they played some incredible tennis. And it happens."

Not to the No 1-ranked Sinner, who is suddenly the favorite to win the men's championship at Flushing Meadows. He won the first five games, and 21 of the first 29 points, to make quite clear how things would go at Arthur Ashe Stadium, before wrapping up a 6-1, 6-4, 6-2 victory over O'Connell in under two hours.

"I felt like he was on from the get-go," O'Connell said. "I felt a little bit clueless, to be honest. Every single shot, I just felt like I had to do something with it, because he was just on me. He was suffocating me."

Stepping on court less than 15 hours after Djokovic's loss to Alexei Popyrin, and two days after Alcaraz's loss to Botic van de Zandschulp, Sinner was as dominant as can be in every facet of the sport. With 23-time major champion Serena Williams watching from a suite, Sinner struck 15 aces. He never faced a break point, he won five of O'Connell's 12 service games and finished with more than twice as many winners, 46, as unforced errors, 22.

"It's the best tennis player I've ever played, for sure," the 30-year-old O'Connell said.

The only past men's champion at the US Open still in the bracket, 2021 winner Daniil Medvedev beat Flavio Cobolli 6-3, 6-4, 6-3 to reach the fourth round, where the Russian fifth seed will face Portugal's Nuno Borges.

Since losing the first set he played in New York against America's Mackenzie McDonald — which was also the first set Sinner had played since news emerged of a doping case that involved two positive tests in March for trace amounts of a banned anabolic steroid — the 23-year-old from Italy has performed impeccably, dropping a total of 18 games across nine sets.

Trying to collect his second Grand Slam title of the year after gaining the first of his career at the Australian Open in January, Sinner will face No 14 Tommy Paul of the United States in the fourth round on Monday. Paul defeated Canadian qualifier Gabriel Diallo 6-7 (5), 6-3, 6-1, 7-6 (3).

"He's a great mover. He has improved a lot. It's going to be a tough challenge," Sinner said about facing Paul, a 2023 Australian Open semifinalist. "He plays some great tennis, especially here in America."

Perhaps there was some wariness on Sinner's part heading into Saturday, given recent events. This is, after all, only the third time in the Open era (the others were in 1973 and 2000) that two of the top three seeded men were gone before the fourth round.

So, Sinner woke up as the man considered likeliest to win the US Open, a status that had belonged to No 3 Alcaraz — the champion at the French Open and Wimbledon this season — before the tournament began. No 2 Djokovic — the defending champ and owner of a men's-record 24 major trophies — became the odds-on favorite when Alcaraz was sent home Thursday night, only to suffer his own early exit Friday night.

The 87th-ranked O'Connell harbored hope of producing yet another surprise, even if he's never beaten a member of the top 10 or been past the third round at a Slam.

What Van de Zandschulp and Popyrin did allowed O'Connell to dream of producing something similar against Sinner.

"I mean, yeah, I've got to believe," O'Connell said, "but, I just felt that he was really on fire."

There is something quite difficult about trying to follow up one career-best win with another, and Van de Zandschulp didn't really show up on Saturday, eliminated by No 25 Jack Draper 6-3, 6-4, 6-2. Draper, a 22-year-old left-hander from Britain, never has been past the fourth round at a major, and neither has his next opponent, unseeded Czech, Tomas Machac, a 6-3, 6-1, 6-2 winner against Belgium's David Goffin.

"After the match (against Alcaraz), it was a little bit crazy," Van de Zandschulp said. "You try to think about the next match, but you get reminded a lot of the match the day before. So, of course it was tough to play today after the last two days."

On the women's side, top-ranked Iga Swiatek, who counts the 2022 title at Flushing Meadows among her five Grand Slam trophies, beat No 25 seed Anastasia Pavlyuchenkova 6-4, 6-2 to reach the fourth round of the US Open for the fourth straight year.

Swiatek said a chat with Serena Williams, as the 23-time Grand Slam champion toured the US Open grounds on Saturday, was a "positive kick".

"It was really nice to see her," Swiatek said. "She has a lot of positive energy. It's nice that she came on-site and she was chatting with the players.

"Even though we met before, and for a couple of years we have been on the same sides and on tour together, I still get star-struck by her," Swiatek said.

"It was nice that she approached me, because I wouldn't, for sure, find courage to do that. She's really nice and really positive."

Earlier Saturday, Jasmine Paolini joined Coco Gauff as the only women to reach at least the fourth round at every major in 2024, getting there at the US Open for the first time with a 6-3, 6-4 victory over No 30 seed Yulia Putintseva.

The fifth-seeded Paolini was the runner-up at the French Open in June and Wimbledon in July, and next meets 2023 French Open finalist Karolina Muchova. Also advancing were No 6 Jessica Pegula, No 16 Liudmila Samsonova, No 18 Diana Shnaider and 2018 Australian Open champion Caroline Wozniacki.

Agencies via Xinhua