Alexander Zverev and Stefanos Tsitsipas booked their spots in the US Open third round, while Novak Djokovic is also through.
Zverev and Tsitsipas, seeded fifth at fourth respectively, were challenged but came through their tests in New York on Wednesday.
The duo shape as two main threats to Djokovic at Flushing Meadows, where the grand slam is being held behind closed doors due to the coronavirus pandemic.
Djokovic remained unbeaten this year on what was a dominant day for the seeds in the men's draw.
ZVEREV, TSITSIPAS CONTINUE RUNS
Zverev did not have things all his own way but was still too good for Brandon Nakashima 7-5 6-7 (8-10) 6-3 6-1.
The German – a semi-finalist at the Australian Open this year – mixed 60 winners with 35 unforced errors to advance in just under three hours.
Next up for Zverev is Adrian Mannarino, the French 32nd seed beating Jack Sock 7-6 (7-5) 7-5 6-2.
Tsitsipas reached the third round of the US Open for the first time after a 7-6 (7-2) 6-3 6-4 win over Maxime Cressy.
The Greek had won just once in his previous two main-draw appearances in New York, but is through to what shapes as an entertaining clash with Borna Coric.
Coric, the Croatian 27th seed, needed more than four hours to overcome Juan Ignacio Londero 7-5 4-6 6-7 (5-7) 6-2 6-3.
DJOKOVIC GOES 25-0
After an early blip, Djokovic got past Brit Kyle Edmund 6-7 (5-7) 6-3 6-4 6-2.
The world number one improved to 25-0 this year as he chases the 18th grand slam title of his career.
"I thought there's a lot of positives in the last couple weeks. Had plenty of match play on the court. I competed great, especially in the last couple of matches during the Cincinnati tournament. Those were very important wins I think mentally for me coming into US Open," Djokovic, who won the Western & Southern Open, said.
"I don't feel tired. I don't feel like energy or recovery is going to be an issue or is an issue for me. In contrary, I actually feel very fit. I love playing best-of-five [sets]. I like my chances best of five on the centre court of US Open against anybody in the world.
"Being experienced player and playing on a big stage for so many times, obviously part of the tour for 15 years, helps in these kind of particular situations.
"I'm just going to do what I know works best for me and hope for the best."
Up next for Djokovic is Jan-Lennard Struff, who claimed a 6-2 6-2 7-5 win over Michael Mmoh.
SEEDS IN COMPLETE CONTROL
The seeds dominated on Wednesday as 11 of the 13 in action reached the third round.
David Goffin, Denis Shapovalov, Taylor Fritz, Filip Krajinovic and Pablo Carreno Busta were among those advancing.
The only two losses came by Cristian Garin, who was edged by Mikhail Kukushkin 6-2 6-1 3-6 4-6 7-5, and Hubert Hurkacz, the Pole falling to Alejandro Davidovich Fokina 6-4 1-6 6-2 6-2.
Source – OPTA