Defenidng US Open champion Coco Gauff was dumped out of the competition on Sunday, blaming a lack of execution in her defeat to fellow American Emma Navarro.

Gauff, who was also comfortably beaten by Navarro at Wimbledon two months ago, fell to a 3-6 6-4 3-6 loss after serving 19 double faults at the Arthur Ashe Stadium.

A bright start from Navarro saw earn a first break in the opening game after two double faults by Gauff in a sign of things to come for the world number three.

Despite a comeback in the second set, Gauff's remaining service games were punctuated by more errors in the third, serving 11 of her total double faults in the final set to hand Navarro the victory. 

"I fought really hard today. I just didn't take care of my serve, so that was the biggest difference," Gauff said.

"Mentally and emotionally I gave it my all. Of course, there were things execution-wise, where I wish I could serve better.

"I think if I would did that, it would have been a different story for me in the match."

Navarro will go on to play 26th seed Paula Badosa in the last eight after the Spaniard thrashed China’s Wang Yafan 6-1 6-2 earlier on Sunday.

Data Debrief: Doubles troubles for Gauff

With 19 double faults, Gauff served the equal-most double faults for her career in a single WTA main draw match, serving as many against Martina Trevisan at Roland Garros in 2020.

Navarro is the first American player to defeat the women’s singles defending champion at the US Open since Serena Williams in 2002 against Venus Williams in the final.

She is also now the player with the most hard court WTA quarter-finals in 2024 (seven, surpassing Elena Rybakina).