NEW YORK — Coco Gauff’s Grand Slam season is over.

For the second consecutive time in a major tournament, Emma Navarro used her increasingly dangerous combination of tenacity, speed and power to defeat Gauff, knocking her out in the fourth round of the US Open 6-3, 4-6, 6-3.

Navarro, 23, who was born in New York and raised in South Carolina, is quickly becoming a major force in tennis. She smothered the reigning champion in front of Serena Williams, Stephen Colbert, Michael Che and nearly 24,000 fans at Arthur Ashe Stadium, playing the match on technical conditions that Gauff could not reasonably counter.

Navarro, who has risen significantly in the rankings over the past year, became an NCAA champion with the Virginia Cavaliers. Now she is No. 13 at her home Grand Slam and she is still climbing, her weaknesses diminishing with each passing month.

“It’s pretty crazy,” Navarro said. “This is the city where I was born and it feels so special to be playing here.”

This was going to be a tough matchup for Gauff no matter what, not least because of the inevitable scar tissue from her Wimbledon loss in July. Gauff went into that match as a favorite not only to beat Navarro but to reach the final, when so many other top players had already fallen. Then Navarro stepped up to the plate and did what she’s been doing all year, really. She ran ball after ball, extended rallies, simply refusing to miss, and held on long enough for Gauff’s Achilles heel—the instability of her forehand and serve—to fail her.

On Sunday, she brought all that and more. Block returns of Gauff’s 120-mph serves went deep enough to send her back down. Stab returns of apparent winners stole points. And on a hot, still, humid afternoon, she proved her fitness is equal to that of Gauff, who is known as just about the fittest player in the game.

Gauff didn’t help herself, double-faulting 19 times, often at key moments. Two double faults gave Navarro a service break in the first set, and another midway through the second gave Navarro a break point. When she saved a Gauff drop shot and hit a forehand down the line for the winner, the end seemed nigh.

Then came the wobbling.

Two ugly service games, full of wild forehands and tentative shot-making, gave Gauff a new lease of life when all seemed lost. She put her finger to her ear to get some more sound as she got the first break of service, and asked the crowd that had rooted her to a trophy 12 months ago to do it all again.

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It was a risky move against a friend, compatriot and Olympic teammate, but she needed all the help she could get. And she certainly wasn’t trying to calm anyone down when she came out on top and the stadium exploded in front of her.

“It was tough to lose the second set. I had chances,” Navarro said.

Gauff’s reprieve was brief. A series of double faults, including two to give Navarro the early break of service in the deciding set, halted her momentum and sent her tumbling. Navarro improved her performance, found new life in her legs and this time did not let the luck of Gauff’s gifts slip from her racket.

“Coco is a great player. I know she’ll come back and win this thing again,” Navarro said.

Emma Navarro’s ironclad play was too much for Coco Gauff at Arthur Ashe Stadium. (Robert Prange/Getty Images)

For Gauff, the loss is the latest in a disappointing summer that began with a semifinal defeat to world No. 1 Iga Swiatek at the French Open. For months before that, going back to August 2023, before she fell triumphantly to the floor in this stadium, she had been one of the most bankable players in the game. She hadn’t cured herself of her weaknesses, but she had found ways to disguise them, playing more safely, hitting big forehands to extend her points and making her matches more physical.

She started to move her throw further back, not wanting to charge up the lane.

Since that loss to Swiatek, opponents have found ways to counter her new strategies. The fickleness in her game that stabilized those strategies is back. Gauff has been out early, for her at least, and in some of the losses, the growing tension between her and her head coach, Brad Gilbert, was obvious.

Coco Gauff’s forehand broke under pressure from Emma Navarro’s fluid ground strokes. (Angela Weiss/AFP via Getty Images)

In the loss to Navarro at Wimbledon, Gauff begged Gilbert to give her a plan to avert the inevitable. In a win earlier in the week, she begged Gilbert and everyone in the box to stop talking to her.

There was little visible tension between Gauff and her box Sunday. But long-term relationships between coaches and players have become increasingly rare.

For Navarro, this victory is a new, solid piece of evidence to support the longer-standing, softer feeling that these two players will spend a lot of time together in the future, at the top of the rankings and in the final rounds of the biggest tournaments. Navarro is three years older than Gauff, but they have known each other since their early years in junior tennis and have been friends. Gauff was a prodigy then, playing two and three age groups higher, and Navarro was just a normally gifted player.

Everything about them seems in contrast. Gauff is a product of the growing black middle class. Navarro is the daughter of a banker and her family is among the wealthiest in the country.

Gauff won matches at Wimbledon at the age of 15, defeating Venus Williams in 2019.

Navarro attended college but blossomed late in life thanks to her reputation as one of the hardest-working players in the sport.

The match ended on her terms.

Gauff double-faulted for match point, then missed a first serve.

From the second inning onwards, Navarro hit the ball deep back, but Gauff again made an error with his forehand.

(Top photo: Robert Prange/Getty Images)