NEW YORK (AP) — Zheng Qinwen was on her back with her arms in the air, celebrating a U.S. Open victory maybe only she believed was possible.

Madison Keys fought off tears as she tried to explain how Zheng, way down and all but out, somehow got the win.

Zheng, the Olympic gold medalist, extended her return to the U.S. Open on Saturday with a spectacular and stunning rally, winning the final seven games to eliminate No. 22 Keys 1-6, 7-6 (3), 7-5.

“I feel like I obviously got off to a really good lead, and then I just got really — I mean, got really scared, like I couldn’t swing,” Keys said. “I don’t know. Tennis just feels really hard right now, so I feel like that kind of took over.”

Hours later, 13th-seeded Naomi Osaka joined her in the fourth round by defeating Elise Mertens 6-3, 3-6, 7-5, in a match that lasted two hours, 38 minutes. The two-time champion from Japan put her head on her racket after the final point, stunned herself at the victory.

“Honestly, I can’t believe I won this match,” Osaka said. “I’m literally shocked that I won this match.”

Not quite as big a comeback as Zheng, but Osaka was down 4-2 in the third set and apologized for expressing so much frustration throughout a tough night.

“There was a certain point, I don’t know, I felt like I put my entire heart on the court and then I just kept trying every single point,” Osaka said. “I didn’t feel like I played amazing, and it was really getting me down. I was very negative on myself.”

Osaka avoided the kind of exit men's No. 9 seed Taylor Fritz endured, blowing a two-set lead and falling to No. 24 Francisco Cerundolo 3-6, 4-6, 6-3, 6-4, 6-4.

“I don’t know how I let that happen today,” Fritz said.

Top seeds knocked out

Amanda Anisimova, like Fritz and Keys a past runner-up at the U.S. Open, also was knocked out when the No. 10 seed lost to No. 24 Anastasia Potapova 6-2, 7-5. No. 5 Flavio Cobolli, the French Open runner-up, lost in four sets to No. 28 Alexander Blockx to leave the men's draw without six of the top 10 seeds.

Keys won a three-set match in the previous round in a match tiebreaker when she fought off five match points. Two days later came a collapse that was as out-of-nowhere as that comeback.

The 2017 runner-up rebounded after losing the second-set tiebreaker to charge out to a 5-0 lead. Zheng held but Keys had a match point while serving at 5-1, and once she couldn't convert that, the turnaround was on, with Keys at one point banging her racket into her head repeatedly and pulling off her visor in disgust.

“I’m just telling myself keep holding every single point, never give up, stay there and somehow little by little it just happened,” Zheng said.

She won the gold medal for China at the 2024 Olympics after reaching the Australian Open final that year, and has been ranked as high as No. 4. But after elbow surgery, she is down to No. 121 and had to go through qualifying just to make the main draw.

“The hard work pays off,” said Zheng, who will play 2022 U.S. Open champion Iga Swiatek next.

Coco Gauff moves on

Coco Gauff, the 2023 U.S. Open champion, beat Cristina Bucsa 6-3, 6-4. Either No. 17 Alex Eala from the Philippines or 14th-seeded American Iva Jovic is up next.

“Honestly, I feel like I’m definitely used to getting to Week 2s now because I feel like I woke up today and I was like, ’Oh, we’re already in Round 3,'” Gauff said. “So, I think that’s a good sign, just feeling like I’m not feeling tired.”

Keys, who won the 2025 Australian Open for her lone Grand Slam title, said she was going to have to make some unspecified changes she has been putting off.

“I think she started playing better; I started playing poorly,” Keys said. “Then I felt like I couldn’t play tennis anymore, and it just felt like it was a much bigger deal than just playing a tennis match all of a sudden.”

Fritz stormed through his first two rounds, losing a total of 11 games, and there was no hint of trouble when he broke Cerundolo to open the third set. But Cerundolo broke right back and started to feel more comfortable in his first time playing in Arthur Ashe Stadium.

“I think fourth and fifth I played a really good tennis that I wasn’t finding that tennis in the previous sets and the previous rounds,” the Argentine said.

Anisimova missed repeated chances by converting just 3 of 16 break-point chances (19%). Potapova, a 25-year-old who was born in Russia but now represents Austria, went 6 for 8 and matched her best showing in a Grand Slam tournament by reaching the fourth round.

Anisimova made the final at both Wimbledon and the U.S. Open in 2025, falling to Aryna Sabalenka in Flushing Meadows. But after reaching the quarterfinals of the Australian Open, the American was eliminated in the third round of the last three majors this year.

Potapova will play No. 5 seed Mirra Andreeva, the French Open champion.

Top-seeded man Alexander Zverev, who had to win five-setters in the first two rounds, faces No. 25 seed Alejandro Tabilo in the nightcap on Ashe.

___

AP Sports Writer Stephen Whyno contributed to this report.

___

See AP’s full tennis coverage here