China's Wang Xiyu stunned third seed Maria Sakkari at the US Open on Wednesday to reach the third round of a Grand Salm for the first time.

Wang, ranked 75, came from a set down to knock out her Greek opponent, who made the semi-finals last year, 3-6, 7-5, 7-5 in their two-hour 43-minute clash.

The left-hander hit 11 aces, 35 winners and saved 12 of 17 break points and goes on to face either Alison Riske-Amritraj of the United States or Camila Osorio of Colombia for a place in the last 16.

"I'm just trying my best to save every ball," 21-year-old Wang said in her on-court interview. "I'm trying and learning."

Wang, the 2018 junior champion at the US Open, was one of four Chinese women to reach the second round along with Zheng Qinwen, Zhang Shuai and Yuan Yue.

Chinese number one Zhang faces Anna Karolina Schmiedlova of Slovakia later Wednesday.

Zheng, who put out former French Open champion Jelena Ostapenko in the first round, takes on Anastasia Potopova on Thursday while Yuan meets Irina-Camelia Begu.

Later Wednesday, China could celebrate seeing a male player making the third round.

Wu Yibing, the first Chinese man in 63 years to win a singles match at a Grand Slam, takes on fellow qualifier Nuno Borges of Portugal.

The 22-year-old Wu, ranked 174, was the first Chinese man to win a US Open singles match since Cheng Guy in 1935 when he knocked out Nikoloz Basilvashili on Monday.

If he defeats Borges, Wu could face world No. 1 and defending champion Daniil Medvedev in the last 32.