The victory continues an impressive resurgence for the reigning Olympic champion, who has endured a difficult period since undergoing elbow surgery in July 2025. Zheng, who previously reached a career-high ranking of world number four, fell outside the top 100 earlier this year as she struggled to rediscover her best form.
However, the 23-year-old Chinese star has found her confidence again in New York.
In her third-round match on Saturday, Zheng appeared to be in serious trouble when she trailed Madison Keys 5-0 in the deciding set. She responded brilliantly, winning seven consecutive games to complete an extraordinary comeback and book her place in the fourth round.
Zheng then found herself in a similar position against eighth seed Swiatek. The Chinese player fell 5-0 behind in the opening set before completely turning the match around. She won 13 of the next 16 games on Arthur Ashe Stadium to secure a convincing 7-5, 6-3 victory.
The second set remained tightly contested early on, with both players holding serve through the opening six games. Zheng then delivered a crucial breakthrough in the seventh game, unleashing a powerful backhand return winner to earn the first break.
She maintained her momentum and broke Swiatek again two games later before serving out the match to seal her place in the last eight.
The victory was Zheng's seventh consecutive win in New York after she successfully came through three qualifying rounds. Her run is also expected to lift her ranking back to the verge of the world's top 50.
"The more matches I play, the more rhythm I have on court," Zheng said after her victory.
She also dismissed concerns about fatigue, saying she arrived in New York feeling fresh and motivated to perform on the tournament's biggest stage.
"I felt really pumped for my match, trying to reach better levels here and enjoy this fantastic stadium," she added.
Zheng will face either Naomi Osaka or Elena Rybakina in the quarter-finals as she continues her impressive US Open campaign.
Elsewhere, French Open champion Mirra Andreeva also secured a place in the quarter-finals after recovering from losing the opening set against Austria's Anastasia Potapova. The result marked the first time Andreeva has reached the last eight at the US Open.
