China's Zheng Qinwen matched her personal best Grand Slam result as she reached the U.S. Open round of 16 by beating Italian Lucia Bronzetti 6-3, 4-6, 6-4 on Saturday. 

Zheng, 20, will next face Tunisian fifth seed Ons Jabeur, who downed Marie Bouzkova from the Czech Republic 5-7, 7-6(5), 6-3.

After establishing an opening lead, Zheng lost the second set when an injured Bronzetti broke in the 10th game to win 6-4, in which Zheng conceded four consecutive points to give her opponent a lifeline to level the match.

Zheng was broken again twice in the decider when Bronzetti took four games straight to lead 4-2, before she put up a fight to break back and take the match in two hours and 39 minutes.

"When you're playing against a good player, these ups and downs can cost you the match, and it almost did today," Zheng reflected.

"I hope I can try to be better in this part. Even if I have a few ups and downs, it's ok, but it shouldn't take me three games, instead one game, or maybe two or three points. That's fine," she added.

When the match was compared to a roller-coaster in a post-match interview, Zheng jokingly responded that the ride is one of her favourite activities in an amusement park.

"I really love the excitement you feel at the highest points. That makes me feel relaxed and free."

Meanwhile, Jabeur scraped by Bouzkova 5-7, 7-6(5), 6-3 to keep her latest U.S. Open campaign on track, firing off 56 winners despite an error-riddled performance.

In the men's singles, top-seeded Carlos Alcaraz of Spain overcame Britain's Daniel Evans 6-2, 6-3, 4-6, 6-3, surviving his first real challenge in New York when Evans mounted a third-set comeback where he broke with a backhand winner.

Alcaraz went 3-2 ahead in the fourth set before breaking Evans in the sixth game with a forehand winner on the run and closed out the match again on forehand, as he continues to defend his title. 

(With input from Reuters)