The fourth-round action on Monday delivered a mixture of dominant performances and dramatic comebacks, with Zheng once again emerging as the headline-maker after recovering from a 5-0 deficit against former US Open champion Swiatek.
Zheng eventually prevailed 7-5, 6-3, completing another extraordinary turnaround just days after she had recovered from 0-5 down in the deciding set against Madison Keys.
Zheng produces another stunning comeback
Zheng's victory over Swiatek was particularly impressive given how quickly the Chinese player found herself in trouble.
The 2022 US Open champion raced into a 5-0 lead in the opening set within 20 minutes, leaving Zheng facing another major fight at a tournament where she has repeatedly demonstrated remarkable resilience.
However, the Olympic champion refused to surrender.
Zheng won seven consecutive games to turn the first set around and eventually take it 7-5. She then maintained her momentum in the second set, winning 6-3 to complete one of the biggest victories of her tournament.
The result also made Zheng the first qualifier since Emma Raducanu in 2021 to reach the women's singles quarter-finals at the US Open. Her run is particularly notable given her battle back from a chronic elbow injury and a significant drop in the rankings.
Rybakina sets up Zheng quarter-final
Zheng's reward is a blockbuster quarter-final against second seed Elena Rybakina, who comfortably defeated former US Open champion Naomi Osaka 6-1, 6-4.
Rybakina's victory also moved her to within one win of becoming world number one for the first time.
The Kazakh entered the tournament with concerns over her fitness after retiring from the Cincinnati Open during the build-up, but she has continued to progress impressively in New York.
Osaka, meanwhile, was hampered by an Achilles tendon injury that had flared up during her previous round.
Gauff continues impressive US Open run
American favourite Coco Gauff also reached the last eight after producing a commanding performance against compatriot Iva Jovic.
The fourth seed won 6-1, 6-4 to set up a quarter-final meeting with French Open champion Mirra Andreeva.
Gauff has now become the sixth American player into the quarter-finals, joining Jessica Pegula, Emma Navarro, Frances Tiafoe, Alex Michelsen and Ben Shelton.
The 2023 US Open champion will face another significant test against Andreeva, who defeated Anastasia Potapova 5-7, 6-4, 6-3 in their fourth-round contest.
Zverev cruises into men's quarter-finals
In the men's singles draw, top seed Alexander Zverev continued his pursuit of a second Grand Slam title with a straight-sets victory over Italy's Luciano Darderi.
The German won 6-2, 6-2, 7-6(3) at Arthur Ashe Stadium to reach the quarter-finals.
Zverev had previously endured two five-set matches during the tournament, making his relatively straightforward victory over Darderi particularly welcome.
The result also represented a measure of revenge for Zverev, who had lost to Darderi at the Italian Open in Rome earlier in the year.
Other notable men's results
• Karen Khachanov defeated American Learner Tien 7-5, 4-6, 6-7(6), 6-1, 6-4.
• Botic van de Zandschulp came from two sets down to defeat Arthur Gea 3-6, 6-7(0), 7-6(7), 7-6(3), 6-4 after a five-hour battle.
• Alexander Blockx defeated 24th seed Francisco Cerundolo 6-3, 4-6, 7-5, 7-5 to reach his first Grand Slam quarter-final.
With the quarter-final line-up now taking shape, the Zheng-Rybakina showdown stands out as one of the most intriguing women's matches of the tournament, with Rybakina chasing the world number one ranking and Zheng attempting to continue her extraordinary run from qualifying to the latter stages of the US Open.