Briton's Kyle Edmund took a set off top seed Novak Djokovic but ultimately struggled to keep up with the world number one's intensity, losing in the US Open second round.
Edmund, 25, unexpectedly won the first set against the Serb, the overwhelming favourite to win the tournament.
But the 33-year-old maintained the level that has helped him stay unbeaten in 2020 and won 6-7 (5-7) 6-3 6-4 6-2.
Djokovic is seeking his 18th Grand Slam title and fourth US Open win.
He will face German 28th seed Jan-Lennard Struff in the third round.
More to follow.