Ryan Harrison and Ivo Karlovic reached the New York Open second round as Sebastian Korda was beaten on his ATP World Tour debut.
Harrison, the sixth seed, overcame fellow American Donald Young 6-3 7-6 (7-4) at the ATP 250 event - which is being played for the first time, replacing the Memphis Open - on Monday.
The final edition of the Memphis Open was won by Harrison, who served 10 aces in his victory over Young.
Karlovic, 38, sent down 20 aces on his way to a 6-4 7-6 (7-4) success over American Jared Donaldson.
Meanwhile, 17-year-old Korda - the son of 1998 Australian Open champion Petr - was beaten.
Korda, who won the junior title in Melbourne to begin the year, was edged out by Frances Tiafoe 4-6 6-4 6-2.
The only seed to fall was Nikoloz Basilashvili, who was upset by Dudi Sela 6-4 6-4.