NEW YORK — Coco Gauff’s US Open title defense ended in a 6-3 4-6 6-3 loss to fellow American Emma Navarro in the fourth round on Sunday, the reigning women’s champion becoming the latest big name to make an early exit at Flushing Meadows this year.

Ms. Gauff had been looking to avenge her fourth-round loss at this year’s Wimbledon but Ms. Navarro stunned the crowd at Arthur Ashe Stadium with an aggressive all-round display to reach the quarterfinals for the first time.

Third seed Ms. Gauff fought her way back into the match after going a set down but ultimately 19 doubles faults and 60 unforced errors meant her first defense of a Grand Slam title was destined to end in disappointment. “Mentally and emotionally, I gave it my all,” said 20-year-old Ms. Gauff, who will now drop out of the top five in the world rankings. “Of course, there were things execution-wise, obviously I wish I could serve better. I think if I would have did that, it would have been a different story for me. But Emma played really well. She did everything well, I thought.”

In men’s action, Alexander Zverev, Grigor Dimitrov, Taylor Fritz and Frances Tiafoe all marched into the quarterfinals in the bottom half of the draw which was left wide open after the third-round exit of four-times champion Novak Djokovic.

Mr. Zverev, still searching for his first Grand Slam title at the age of 27, reached the quarterfinals at a major for the 13th time after coming from a set down to beat American Brandon Nakashima 3-6 6-1 6-2 6-2.

The fourth seed will next face another American in Mr. Fritz, who overcame a sluggish start to beat Norwegian Casper Ruud, the losing finalist in 2022, 3-6 6-4 6-3 6-2.

HOMEGROWN CHAMPION
Mr. Fritz was later joined in the quarterfinals by Mr. Tiafoe, another player hoping to take advantage of the early exits of Mr. Djokovic and Carlos Alcaraz to end America’s 21-year wait for a homegrown men’s champion.

Alexei Popyrin ousted Mr. Djokovic in a huge shock on Friday but was unable to progress any further as Mr. Tiafoe, roared on by a noisy evening crowd on Arthur Ashe, ran out a 6-4 7-6(3) 2-6 6-3 winner.

It was not all plain-sailing for the 20th seeded American, who had to dig deep to battle back from 5-2 down in the second set against the big-serving Australian.

Mr. Tiafoe, though, broke for 4-2 in the fourth on a Popyrin double fault and held firm to set up a quarterfinal against Mr. Dimitrov, who was earlier cheered on by Serena Williams as he downed sixth seed Andrey Rublev 6-3 7-6(3) 1-6 3-6 6-3.

Women’s second seed Aryna Sabalenka, the runner-up to Ms. Gauff last year, continued her impressive form to move into the last eight with a 6-2 6-4 victory over her former doubles partner Elise Mertens.

The twice Australian Open champion was in imperious form in the first set, rock solid on her booming first serve, coming into the net to great effect, and regularly unleashing her rocket of a forehand.

Belgian Ms. Mertens made things trickier in the second stanza and the Belarusian was forced to save four break points but another 23 winners to take her match tally to 41 saw Ms. Sabalenka safely into the quarterfinals for the fourth straight year.

Ms. Navarro, meanwhile, moves on to play Spain’s Paula Badosa, who thrashed Wang Yafan of China 6-1 6-2 in the first match of the day at Louis Armstrong Stadium to reach the last eight in New York for the first time. — Reuters