Two-time defending champion Aryna Sabalenka earned one of the quickest Grand Slam wins of her career with a 53-minute pummelling of US Open debutant Polina Iatcenko in the second round.
However, the world number one did not look entirely happy even as she swept aside Iatcenko - then had a spiky exchange with a reporter in her post-match news conference.
Sabalenka, 28, is aiming to win her first major title of a strange season where she has enjoyed spectacular success but is now looking to recover from a recent dip.
Coasting to a 6-1 6-1 victory over 22-year-old qualifier Iatcenko did not offer a true test of where Sabalenka's level is.
But the ruthless manner in which she secured victory will certainly boost confidence as she looks to complete a rare 'three-peat' of US Open titles.
"I'm happy with the level I played, happy with the focus and happy to be through this match," said Sabalenka, who will play Uzbekistan's Kamilla Rakhimova in the third round.
Sabalenka knows she must the lift the trophy in New York again to stand any chance of preventing Elena Rybakina taking her position at the top of the rankings.
Even if Sabalenka does retain the title, Rybakina would still rise to the summit by reaching the semi-finals.
Sabalenka losing the top spot seemed unthinkable after a storming start to the season, reaching the Australian Open final and winning the Indian Wells and Miami titles back-to-back.
Losing to Rybakina in Melbourne was Sabalenka's only defeat in her first 27 matches of 2026. After completing the Sunshine Double, her win-loss record dropped to 17-7 leading into the US Open and she has only reached one WTA semi-final in the past five months.
Before the final Grand Slam of the season, Sabalenka admitted she had been "dealing with several things" in a period which she knows was far below her best.
And, after beating Iatcenko, Sabalenka took umbrage with what she perceived to be a suggestion from a reporter that she had been attending "lots of parties" in the build-up to the US Open.
"What kind of question is that? Just because I posted some activities with brands, you think that I've been partying [and] not training?" countered Sabalenka.
Asked if she was "getting serious" now the tournament was under way, she said: "Oh yeah, I wasn't serious before that. Next question."
Sabalenka's pace and power was too much for world number 160 Iatcenko, who managed just three winners compared to the 24 put away by the top seed.
Iatcenko looked a bundle of nerves in the biggest match of her career, but composed herself to get on the scoreboard for 5-1 and immediately broke out into a relieved smile.
It was merely respite as Sabalenka held to love in less than 90 seconds to clinch the opening set.
Despite only being on court for 24 minutes, Iatchenko decided she wanted a bathroom break to change her kit - but more likely for a mental reset than anything else.
Sabalenka kept loose while she waited by practising her serves and maintained her rhythm as she surged a double break ahead for 3-0 in the second set.
It was not all plain-sailing for Sabalenka as she lost serve in a sloppy fourth game, but reasserted her authority with two more breaks as Iatchenko was taught a harsh lesson.
The Russian can console herself with the knowledge she has gained valuable experience against the world number one on the biggest court on the planet - and a bumper paycheck.
Coming into the US Open, she had earned $300,000 (£220,000) in her career but takes another $190,000 (£140,000) home from New York to reinvest into her future.
Earlier on Wednesday, third seed Pegula continued her quest for a maiden Grand Slam singles title with a comfortable victory over fellow American Sofia Kenin.
Pegula also has a shot of replacing Sabalenka as world number one if she wins the title, as does fourth seed Coco Gauff, and kept her dream alive with a 6-3 6-1 win.
There were also straight-set wins for Wimbledon runner-up Karolina Muchova, two-time major semi-finalist Marta Kostyuk and teenage American sensation Iva Jovic as the patten of few shocks in the women's draw over the opening two rounds continued.
