Heather Watson and Jubb failed to reach the main draw of the US Open. Former British number one Watson (30) was defeated 3-6, 6-4, 7-5 by 16-year-old Czech Sara Bejlek.
Jubb, a 22-year-old Dutchman ranked 203 in the world, fell to Gijs Brouwer 7-6 (7-3) 3-6 6-2.
Monday marks the beginning of the year’s last Grand Slam in Flushing Meadows in New York.
Two British women will compete in the singles draw due to Watson’s loss; reigning champion Emma Raducanu and Harriet Dart have already qualified as direct entrants.
Jubb wanted to compete in the men’s draw with Andy Murray, Cameron Norrie, Dan Evans, Jack Draper, and Kyle Edmund.