New York, New York - Coco Gauff joined Novak Djokovic and Carlos Alcaraz in exiting the US Open tennis tournament Sunday as the defending champion crashed out to Emma Navarro in a blizzard of mistakes.

As Gauff exited, US hopes were then rekindled when Frances Tiafoe and Taylor Fritz reached the men's last-eight, igniting dreams of a first homegrown male Grand Slam champion since Andy Roddick's win in New York in 2003.

Third-ranked Gauff slumped to a 6-3, 4-6, 6-3 fourth round defeat to her American teammate 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 Navarro, who will face Spain's Paula Badosa for a place in the semi-finals.

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.

"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.

Tiafoe joined former champions Andre Agassi, Roddick, and Pete Sampras as the only American men to reach at least three US Open quarter-finals since 2000.

The 20th-ranked Tiafoe notched a 6-4, 7-6 (7/3), 2-6, 6-3 victory over Alexei Popyrin, who shocked Djokovic in the last round.

Tiafoe will face Bulgarian veteran Grigor Dimitrov for a place in the semi-finals.

The 26-year-old is the second American man in the quarter-finals after Fritz defeated Casper Ruud earlier in the day.

Tommy Paul can make it three, but he has to get past world number one Jannik Sinner on Monday.

"I used to hit the ball off a wall dreaming about playing on Arthur Ashe Stadium where the Williams sisters won and where (Roger) Federer won like a million times," said Tiafoe.

"I want to be part of that. This court brings out the best in me."

Dimitrov, the ninth seed, put out Russian sixth seed Andrey Rublev, 6-3, 7-6 (7/3), 1-6, 3-6, 6-3 to return to the quarter-finals for the first time since 2019 when he defeated Federer in what proved to be the Swiss legend's final appearance in New York.

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 US, 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 12th seed 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.

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.

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.