Sabalenka will play third-seeded Jessica Pegula in Thursday night’s semi-finals — the first time since 1975 at the US Open that the top four women all made it to the penultimate round.
Top-seeded Alexander Zverev completed the men’s semi-final lineup, cruising past Botic van de Zandschulp 6-2, 7-5, 6-1.
Gauff made it by the skin of her teeth, struggling early and saving two match points in the tiebreaker.
She rallied with some inspiration from Frances Tiafoe’s come-from-behind five-
set victory over Alex Michelsen.
“I just had to reset,” Gauff said. “Honestly, I was thinking about Frances Tiafoe and how he came back. I was just trying to leave the court without regrets.”
Rybakina, the first Kazakh player to reach number one, is chasing a third Grand Slam title after winning the Australian Open in January — four years after winning Wimbledon.
“I feel like you will appreciate and think about it even more when you finish your career,” she said of the ranking. “Like now, you still need to keep on going.”
Reigning Olympic champion Zheng, a former world number four ranked 121 after missing about eight months due to elbow surgery, went through qualifying and won seven matches in New York, including comeback wins over six-time Grand Slam champion Iga Swiatek and former Australian Open winner Madison Keys.
She rocked Rybakina early behind fierce serve and a variety of shots, effectively neutralizing the Kazakh’s power until a slight dip allowed Rybakina to seize control in the second set.