China's Wang Zhiyi downed world No. 1 An Se-young of South Korea 21-12, 21-16 to reach the women's singles quarterfinal at the badminton China Masters in Shenzhen on Thursday, setting up her next match with Japan's Nozomi Okuhara.

Wang, 23, had suffered four straight defeats to An this season and went into Thursday's encounter with an overall 1-7 head-to-head record against the world No. 1.

An, 21, has won 10 singles titles out of the 13 finals she reached this season, including victories at the World Championships and the Hangzhou Asian Games. She also won the team title representing South Korea at the Hangzhou Asiad.

She has since, however, suffered from a right knee injury that almost cost her the title in Hangzhou against home favorite Chen Yufei in the women's singles final, which was South Korea's second ever badminton singles title in Asiad history. A troubled An lost to Chen last week in the semifinal round of the Japan Masters before falling short to 12th-ranked Wang this time.

Wang claimed an easy win in the opening game and managed to hold off An when the South Korean came back from behind to level the second game 14-14, wrapping up the match in 47 minutes. 

"I really enjoy playing in China, the atmosphere is great and the crowd was always cheering me on, which gave me a lot of motivation to win point by point," said Wang after the match. 

"This is a small achievement for me and I've been eager to make a breakthrough on the court to defeat some of the top players. Compared to the past few matches with her, I think I played with more determination and patience today. Because she is a very strong opponent, a very good defensive player, she's not easy to beat, so I think I did a good job of being patient today."

Later on Thursday, Chinese duo Zheng Siwei and Huang Yaiqiong downed Japanese pair Kyohei Yamashita and Naru Shinoya 21-17, 21-13 to reach the mixed doubles quarterfinal round.