Defending champion Coco Gauff has been sent packing from the US Open, losing to fellow American Emma Navarro 6-3 4-6 6-3 in the fourth round.

Third seed Gauff was unable to overcome a poor performance that included more double-faults, 19, than winners, 14.

World No.12 Navarro, who also eliminated Gauff in the fourth round at Wimbledon in July, was far steadier on Sunday.

Gauff, 20, had won 10 matches in a row at Flushing Meadows, including the run to her first grand slam title a year ago.

But this was the latest in a series of early-for-her exits in recent weeks, including bowing out in the third round at the Paris Olympics, then going 1-2 at hard-court tuneup events before arriving in New York.

After each of her past two contests in New York, Gauff headed back out onto the practice courts to work on her serve.

That didn’t help much on Sunday. Eleven of her double-faults came in the final set alone.

She described her serve problems as “more of an emotional, mental thing”.

“Because if I go out on the practice court right now, I would make, like, 30 serves in a row. I’ve done it before,” she said.

I think it’s also just kind of a mental hurdle that I have to get over when it comes. … But I definitely want to look at other things, because I don’t want to lose matches like this anymore.”

Aside from those issues, Gauff finished with a total of 60 unforced errors – a whopping 29 on her forehand side, the biggest weakness in her game.

This result follows the surprising third-round loss by defending men’s champion Novak Djokovic on Friday night, meaning the lengthy droughts without anyone winning consecutive titles in New York will continue.

The last woman to win at least two in a row was Serena Williams with three from 2012-14; the last man was Roger Federer with five from 2004-08.

The Wimbledon win over Gauff earned Navarro, the 2021 NCAA singles champion for the University of Virginia, her first appearance in a major quarter-final.

Her second will come on Tuesday in New York against No.26 seed Paula Badosa, a 6-1 6-2 winner against Wang Yafan.

That will give Navarro another chance to play at Arthur Ashe Stadium in front of a big crowd. She’d never hit a ball in the place until Sunday — and felt rather at ease, anyway.

“I’ve been out on big courts before, where I just felt totally overwhelmed and almost like it’s an out-of-body experience. But I didn’t feel like that today,” Navarro said.

“I felt comfortable from the time I stepped out onto the court,which I was a little bit surprised about. I kind of had prepared myself for the worst, just in terms of feeling overwhelmed and nervous.”

-AAP