Sabalenka, who is going to be the No. 1 player in the WTA rankings next week after Iga Swiatek lost in the fourth round, has not dropped a set at Flushing Meadows and has ceded a total of 21 games through five matches.
She cruised through her quarterfinal in heat that approached 95 degrees and prompted a partial closing of the Arthur Ashe Stadium roof to provide more shade for spectators and players.
The No. 2-seeded player from Belarus has made the past five Grand Slam semifinals, winning her lone major at the Australian Open in January. She became the first woman to reach all four major semifinals in one season since Serena Williams in 2016.
“I just gave myself another opportunity to do better in the semis,” Sabalenka said in her postmatch interview. “I still have things to do in New York. … I’ll think about being the world No. 1 after the US Open.”
Zheng, a 20-year-old from China who reached her first Grand Slam quarterfinals by taking out No. 5 seed Ons Jabeur, fought off a match point with an ace. But she got just 41% of her first serves in play and won just three points against Sabalenka’s first serve.
Russian players Daniil Medvedev and Andrey Rublev are playing Thursday afternoon for a spot in the semifinals. Medvedev or Rublev will meet the winner of the nightcap between defending champion Carlos Alcaraz and No. 12 Alexander Zverev.
The Associated Press contributed to this report.