Twelfth seed Richard Gasquet crashed out of the US Open in the first round after a five-set defeat to Tommy Haas.
Haas, who has reached the quarter-finals in each of the last two years, was always likely to be a dangerous opponent for the Frenchman and so it proved as the former world number three prevailed 6-7 6-4 5-7 7-5 6-2.
Gasquet was his own worst enemy as he committed 64 unforced errors as he became the highest-seeded player to lose in the early stages of the tournament.
Number 13 seed Fernando Verdasco coasted into the second round with a 6-3 6-4 6-1 triumph over Igor Kunitsyn.
Fourteenth seed Ivo Karlovic of Croatia booked a spot in the second round with a 7-5 6-1 6-4 triumph over Jan Minar.
Upset
American Sam Querrey managed to post a mild upset with a 6-3 6-1 6-2 triumph over number 22 seed Tomas Berdych.
Ranked 55th in the world, Querrey has failed to make it past the second round in his first two appearances at this hardcourt Grand Slam.
Querrey was outstanding against his Czech opponent, winning 88% (35 of 40) of his first serves.
"It's a big one," said Querrey.
"The last three or four tournaments I've gone out pretty early with tough players, so it's nice, especially at the Grand Slam in your own country, to get off to a good start."
It was a disappointing result for Berdych, who reached the fourth round here last year.
Other winners early winners included number 15 seed Tommy Robredo, Jarkko Nieminen, Nicolas Devilder and Florent Serra.
