Defending champion Aryna Sabalenka pulled off a stunning victory at the US Open final over American Amanda Anisimova, 6-3, 7-6(3), to become the first woman to win back-to-back singles titles since Serena Williams in 2014.
Gauff lost the game by a margin of 6-3, 4-6, 6-3, which let Navarro reach her second successive major quarterfinal and ended Gauff's title defence and 11-match win streak in New York.
In a span of 40 days, Gauff has won three huge titles and a total of 18 out of her 19 previous matches. She previously won the Washington Open and Cincinnati Open in August.