Coco Gauff, of the United States, celebrates after defeating Zhang Shuai, of China, during the fourth round of the US Open tennis championships, Sept 4, 2022, in New York. (JULIA NIKHINSON / AP)

Coco Gauff raised a fist, then wagged her right index finger, responding to, and riling up even more, a loud-louder-loudest Arthur Ashe Stadium crowd that was standing and screaming. Gauff's US Open opponent, China's Zhang Shuai, covered both ears with her hands.

Gauff and her fans were reacting excitedly to quite a point, one in which the 18-year-old Floridian raced to her right for a defensive forehand, then changed directions to sprint and slide into a backhand that drew a netted volley from Zhang. Just four points later, Gauff was a quarterfinalist at Flushing Meadows for the first time.

Gauff, the French Open runner-up in June, came back in each set to beat Zhang 7-5, 7-5 on Sunday to become the youngest American to make it this far at the US Open since Melanie Oudin was 17 in 2009

Gauff, the French Open runner-up in June, came back in each set to beat Zhang 7-5, 7-5 on Sunday to become the youngest American to make it this far at the US Open since Melanie Oudin was 17 in 2009.

"Here, I can't hear myself scream. Makes me want to do it more. I think I'm feeding off the momentum a lot. I enjoy it," said No 12 seed Gauff, who will meet No 17 Caroline Garcia of France on Tuesday. "New York is bringing out a side of me that I haven't had since I was 15, so it's nice."

After trailing 5-4 in the opening set, then 5-3 in the second, which she was a point from losing, Gauff was buoyed by spectators who cheered her every point and chanted "Let's go, Coco!" as the end neared. She improved to 4-0 in Ashe this year after having never previously won a match at the biggest arena in Grand Slam tennis.

How loud was it?

"It got so raucous in there that I got a headache. I had to take an Advil," said Gauff's father, Corey. "I kept pinching myself. I'm like, 'My gosh, all of these people here for my daughter.' You dream about this, but you never know if you're going to realize that. She was pumping herself up and they responded to her. It sent chills up my spine."

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Zhang, at 33 the oldest woman to reach the fourth round, and Gauff competed mostly from the baseline, trading powerful groundstrokes, especially on the backhand side, which both players favor. The longer the exchanges, the more success Gauff found: She claimed a 45-26 edge in points that lasted five or more strokes.

Garcia is coming off a hard-court title at Cincinnati and stretched her winning streak to 12 matches by eliminating No 29 Alison Riske-Amritraj of the US 6-4, 6-1.

"I'm super excited, actually, to play Coco－in US, in New York, quarterfinal of a Slam. It's great," Garcia said.

None of the eight women in action on Sunday had ever been past the fourth round at Flushing Meadows; only two have reached semifinals at any Grand Slam tournament: Gauff and No 5 Ons Jabeur.

During Gauff's win, the whirring of the Ashe retractable roof being pulled shut accompanied the start of the second set because of showers that started soon after, and it took a while for the artificial lights to reach full strength. The match proceeded, even though it was rather dark－and quite humid－indoors.

Zhang started getting the better of the back-and-forth midway through the second set, and when she hit a backhand winner of her own, she broke to lead 5-3.

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Last year's US Open doubles champion－she and Sam Stosur beat Gauff and Caty McNally in the final－served to force a third set, and was a point away from getting there, but Gauff steeled herself and stood her ground.

That set point was frittered away when Zhang sent a backhand long. Gauff smacked a down-the-line backhand winner for her third break point of that game, then delivered a good return to a corner that drew a long backhand to make it 5-4 and start a four-game, match-closing run.

Everyone's known how talented Gauff is for a while now. At 15, she became the youngest qualifier in Wimbledon history in 2019, beating Venus Williams in the first round of the main draw and made it all the way to the fourth. There have been more steps along the way, more achievements, including last month becoming the second-youngest doubles No 1 in WTA history.