Jannik Sinner extended his winning Grand Slam run on hard courts to 23 matches with a comfortable victory over Alexei Popyrin.
The Italian is bidding to do the double-double on the surface having won back-to-back Australian Opens as well as the US Open 12 months ago.
He is undoubtedly the man to beat in New York, particularly after winning a first Wimbledon title, and a 6-3 6-2 6-2 victory over the dangerous Popyrin means he has dropped just 11 games in the first two rounds.
Australian Popyrin pulled off the win of his life at Flushing Meadows last summer, beating Novak Djokovic in the third round, but he scarcely managed to lay a glove on Sinner.
The world No1, who next faces 27th seed Denis Shapovalov, did not have his best serving day but he saved all five break points he faced and remains on track to become the first man since Roger Federer won five successive titles from 2004 to 2008 to retain the trophy.
Tenth seed Lorenzo Musetti swept aside veteran David Goffin 6-4 6-0 6-2 while Coleman Wong's 7-6 (5) 6-2 4-6 6-4 victory over Adam Walton made him the first man from Hong Kong to reach the third round at a Grand Slam.
In the women’s draw, Iga Swiatek survived a second-round wobble to progress at the US Open.
The second seed arrived in New York as the form player on the women's tour after following up her Wimbledon title by winning the WTA 1000 event in Cincinnati.
She had looked full of confidence in her first match but made a host of errors in the second set against Dutchwoman Suzan Lamens before coming through 6-1 4-6 6-4.
From 4-3 up in the second set after a one-sided first, Swiatek tightened up and lost four games in a row as Lamens, ranked 66, forced a deciding set.
Lamens fought back again after going 4-1 down but Swiatek kept her nerve this time to set up what could be another battle against 29th seed Anna Kalinskaya.
Swaitek said: "It wasn't an easy match and I made some mistakes. I'm happy that at the end I could be more proactive.
"I probably got a little tight in the second set and she used the opportunity and was using her chances. It was not easy, but the third set is a reset."
