Coco Gauff’s defence of her first major title was marred by a flurry of double faults, as she lost in three sets to compatriot Emma Navarro.

The result was a continuation of the unpredictable story of this US Open, which has already lost two of its biggest male stars: Novak Djokovic and Carlos Alcaraz.

Since Serena Williams last played here two years ago, Gauff has become the most recognizable name in American tennis (among active players, at least). She lived up to her promise by winning the US Open last summer at just 19.

At the time, it seemed that Gauff’s breakthrough would mark a turning point in her career, heralding an imperial period in which she would win multiple trophies.

A year later, that hasn’t quite happened. Even though Gauff remains one of the most consistent players on the WTA Tour (she and Jasmine Paolini are the only women to reach the fourth round of all four majors this season), she has added just one title to her collection, and that came in the relatively subdued season opener in Auckland.

Gauff’s persistent technical problems were all too apparent against Navarro, a good and consistent hitter who had also knocked her out at Wimbledon this summer.