Defending champion Coco Gauff became the latest big-name casualty to exit the US Open when Emma Navarro won their fourth round match 6-3 4-6 6-3 to beat her stunned American compatriot at a Grand Slam for the second time this year.
Gauff had been looking to avenge her defeat by Navarro at Wimbledon, where she lost in the fourth round, but the 13th seed stunned the crowd at Arthur Ashe Stadium with an aggressive and dominant all-round display.
Gauff was her own worst enemy, however, especially on serve where the 20-year-old had 19 double faults, as many as she had in her first three matches combined, while she also made 60 unforced errors.
The third seed said she needed to find more consistency on her delivery and was open to the idea of bringing in a specialist coach to work on her serve.
Navarro's victory moved her into a second Grand Slam quarter-final where she will play Spain's 26th seed Paula Badosa, while defeat for Gauff will see her drop out of the top five in the world rankings.
Navarro was stunned to reach the last eight after falling at the first hurdle in previous years.
"I lost in the first round (in the) last two years and now to be making quarter-finals is pretty insane," she added. "This is the city I was born in and it feels so special to be playing here.
"Coco's an amazing player and I have a ton of respect for her. I know she's going to come back here and win this thing again one year."
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