Great Britain's Heather Watson, Paul Japp and Sonai Kartal advanced to the first round of qualifying for the US Open.
Former British number one Watson stunned last year's Junior Wimbledon champion Klarvi Nukuno with a 6-1 6-1 win in 69 minutes.
Despite finishing 33 places lower than his compatriot, Jupp, world number 193, defeated Jacob Fearnley 6-1 7-6 (7-2) to win an all-British clash.
Kartal, who reached the third round at Wimbledon this year, won 6-3 6-3 against Spain's Cuomar Maristani before falling to second seed Coco Goff.
Liam Brady, however, was disappointed, losing 7-5 7-6 (9-7) to Finland's Otto Virtanen.
Brady, 30, missed the start of the grass-court season after hitting his head on the boot of his car and suffering a concussion.
Billy Harris, John Soinski, Oliver Crawford, Fran Jones and Lily Miyazaki will play in the first round of qualifying on Tuesday.
The main tournament at Flushing Meadows begins on August 26.