"I am happy with my performance this week. I have shown my tennis, tried different tactics, and added some new elements to my game. Even the match today with Iga, I think I can really learn something from her," said Zheng.

On the men's side, it was not a good day for high-ranked seeded players, as Daniil Medvedev and Stefanos Tsitsipas were both knocked out in the last eight.

World No.2 Medvedev was thrashed 6-2, 6-3, 6-2 by 2014 US Open champion Marin Cilic in the night session on the central court, while fourth-seeded Tsitsipas, who was last year's finalist, was shocked by Denmark's sensational teenager Holger Rune 7-5, 3-6, 6-3, 6-4.

Rune takes on Casper Ruud in the quarterfinals, while 33-year-old Cilic takes on another Russian player, seventh seed Andrey Rublev.