British qualifier Lily Miyazaki saw her memorable US Open run come to an end with a second-round exit against Olympic champion Belinda Bencic.
Miyazaki, 27, had never qualified for a Grand Slam main draw until she won three matches to reach the first round.
The British number seven backed that up with a straight-set victory over Russia's Margarita Betova.
But Bencic was a different proposition and Miyazaki, despite frustrating the Swiss 15th seed, was beaten 6-3 6-3.
Miyazaki lost her serve for a fourth time in what proved to be the final game, becoming the first Briton to lose in the singles at Flushing Meadows this year.