Coco Gauff joined Novak Djokovic and Carlos Alcaraz on the US Open scrap-heap Sunday as the defending champion crashed out to Emma Navarro in a blizzard of mistakes.

Third-ranked Gauff slumped to a 6-3, 4-6, 6-3 fourth round defeat on the back of 19 double faults and 60 unforced errors.

The 20-year-old's exit means Serena Williams remains the last woman to successfully defend the US Open title back in 2014.

"I lost in the first round the last two years and now to be making the quarter-finals is pretty insane," said fellow American Navarro, who will face Spain's Paula Badosa for a place in the semi-finals.

"This is the city I was born in and it feels so special to be playing here. Coco is an amazing player. I have a ton of respect for her and I know she's going to come back here and win this thing again."

Gauff's loss was another body blow to the season's final Grand Slam.

Djokovic, the defending men's champion, was knocked out in the third round to suffer his earliest exit in 18 years.

Fellow crowd-pleaser Alcaraz, the 2022 winner in New York and reigning French Open and Wimbledon champion, was stunned in the second round.

- 'Gave it my all' -

"I gave it my all," said Gauff. "Obviously there were things execution-wise, where I was like, I wish I could serve better. I think if I did that, it would have been a different story."

Navarro had defeated Gauff at Wimbledon in July and was dominant again on Sunday from the outset.

The 23-year-old broke for 4-2 in the first set and sealed the opener in the ninth game where one rally stretched to 27 shots.

Gauff recovered from a break down in the second set to level the tie, but it was a brief respite as she served up three more double faults in the third game of the decider to slip a crucial break down again.

New York-born Badosa reached her first US Open quarter-final with a 6-1, 6-2 win over China's Wang Yafan.

Despite the one-sided scoreline, the first two games took 17 minutes. Badosa saved all eight break points she faced.

"It was so humid I thought I was going to die," said the 26-year-old.

Alexander Zverev, who blew a two-set lead to lose the 2020 final to Dominic Thiem, made his fourth quarter-final by beating Brandon Nakashima of the United States, 3-6, 6-1, 6-2, 6-2.

Fourth-ranked Zverev served 14 aces and clubbed 51 winners past the 50th-ranked Nakashima.

Up next is a last-eight clash with US 12th seed Taylor Fritz, who came back from two sets down to triumph in the pair's dramatic fourth round clash at Wimbledon in July.

"That was an amazing match. I expect a tough battle -- it always is when I face Taylor," said Zverev.

Fritz knocked out 2022 runner-up and eighth-ranked Casper Ruud 3-6, 6-4, 6-3, 6-2 on the back of 24 aces to reach his third Grand Slam quarter-final of the year.

- 'Stay patient' -

Alexei Popyrin, the 28th-ranked Australian who shocked 24-time major winner Djokovic, has yet to make a Slam quarter-final.

In the night session, he was battling flamboyant Frances Tiafoe, the 20th-ranked shot-maker who made the semi-finals in 2022 and last-eight 12 months ago.

With Djokovic and Alcaraz eliminated, home fans are dreaming of a first American men's Grand Slam champion since Andy Roddick captured the US Open in 2003.

Waiting in the quarter-finals will be Grigor Dimitrov, the ninth-seeded Bulgarian who put out Russian sixth seed Andrey Rublev, 6-3, 7-6 (7/3), 1-6, 3-6, 6-3.

Dimitrov last made the quarter-finals in 2019 when he defeated Roger Federer in five sets in what proved to be the Swiss legend's final appearance in New York.

"I was playing fairly good today in the first two sets," said 33-year-old Dimitrov, the oldest player left in the men's draw.

"But for some reason, my body got tired a little bit and he wasn't going to give up the match. I had to stay patient."

Women's second seed and Australian Open champion Aryna Sabalenka, runner-up to Gauff last year, eased into a fourth successive quarter-final by seeing off Belgium's Elise Mertens 6-2, 6-4, unleashing 41 winners.

Sabalenka will next face either Zheng Qinwen or Donna Vekic who were facing off in a repeat of the Olympic Games final won by the Chinese star.