British number one Katie Boulter suffered a heavy 6-1 6-0 defeat to Czech seventh seed Karolina Muchova in the US Open second round, winning just one game in a match lasting only 58 minutes. Boulter described it as "a bad day at the office", saying she struggled with the conditions and noise after the match was moved to the 14,000-capacity Louis Armstrong Stadium due to rain, and admitted she let the surroundings distract her. The result adds to a difficult season for the world number 62, who has now won just two of her last six matches since a first-round exit at Wimbledon.

Boulter's serve was a particular weakness, with eight double faults, no aces, and only 33% of points won behind her first serve, while she committed 22 unforced errors to just four winners and failed to save any of seven break points. By contrast, Wimbledon runner-up Muchova produced 14 winners against just nine unforced errors. Elsewhere, fellow Briton Jacob Fearnley lost in four sets to Argentina's Tomas Martin Etcheverry, while Francesca Jones fought back from a rain-interrupted match to beat Poland's Magda Linette in three sets, securing only her second Grand Slam victory.