Zheng Qinwen and Yuan Yue joined compatriots Wang Xiyu and Zhang Shuai in the third round of the U.S. Open on Thursday – the first time in history four women from China have reached the last 32 of a single Grand Slam event.

Zheng, 19, beat Anastasia Potapova of Russia 7-6 (4), 7-6 (3) in a hard fight, while Yuan defeated Romanian veteran Irina-Camelia Begu 6-3, 7-6 (6).

World No. 39 Zheng, who hit 10 aces thanks to her powerful serve, seesawed with her 21-year-old opponent until 6-6 in the opening set and once trailed at 4-1 in the tiebreaker, but took six points in a row to wrap it up 7-4. 

The two exchanged breaks several times in the second set before Zheng sealed victory by winning the tiebreaker 7-3. 

Rising star Zheng, who reached the last 16 at the French Open earlier this year, edged out former French Open champion Jelena Ostapenko in three sets in her U.S. Open debut on Tuesday. 

She will next face World No. 108 German Jule Niemeier, who upset Yulia Putintseva 6-4, 6-3.

Meanwhile, 23-year-old U.S. Open debutante Yuan had already achieved her best result at a Grand Slam tournament by reaching the second round after beating Australia's wild card Jaimee Fourlis 6-3, 6-2 on Tuesday. 

The world No. 142 opened the match by winning three games in a row before taking the first set 6-3. 

Yuan shared the spoils with Begu after 12 games in the second set, but kept resilient to win the tiebreaker 8-6. Yuan will next challenge American Jessica Pegula, who is seeded eighth.

Zheng said on Thursday that China's contingent in New York is feeding off the energy of each other's successes.

"This is so positive. It means in China the tennis starts to go up," she said.

"Between each other, we have really good competition. When you have someone to compete, you always can perform better.

"I think with this energy, I hope all of us, we can going as far as we can. Such good performance here, I'm happy for all of them."

Zheng said her consistency at Grand Slams this year is the result of hard graft on the practice court combined with her dogged determination to succeed.

"I always say that Slam is one of my dreams since I was little," she said. "So every time when I arrive here, I will leave everything I have on the court."

In the women's doubles first round, Chinese pair Xu Yifan and Yang Zhaoxuan came from behind to beat their compatriot Han Xinyun and Russia's Evgeniya Rodina 3-6, 6-1, 6-2, while Chinese veteran Zhang Shuai paired up with Marta Kostyuk of Ukraine to defeat Nadiia Kichenok of Ukraine and Georgian Oksana Kalashnikova 6-4, 6-4 to reach last 32.

Zhang, 33, already has two Grand Slam doubles titles to her name and came to New York as the women's doubles defending champion.

In other games, world No.1 Iga Swiatek cruised past the 2017 champion, American Sloane Stephens, 6-3 6-2 as the last of the top four seeds remaining at the U.S. Open after world No. 2 Anett Kontaveit lost to Serena Williams on Wednesday and hard-hitting Greek Maria Sakkari and Spain's Paula Badosa also fell in the second round.

Two-time Grand Slam champion, Belarus' Victoria Azarenka, who has reached the final of the U.S. Open on three previous occasions, sealed a 6-2, 6-3 win with a largely tension-free straight sets victory over Ukraine's Marta Kostyuk. 

On the men's side, Spanish teenager Carlos Alcaraz fended off a late push from veteran Argentine Federico Coria to emerge with a 6-2 6-1 7-5 win to reach the U.S. Open third round, where he will face American Jenson Brooksby.

(With input from agencies)