Wang lost both matches to the 37-year-old American at Grand Slam tournaments last year, the French Open and Wimbledon respectively, reports Xinhua news agency.
Wang, who made it to the main draw at Roland Garros for the fourth time, finished her first break after both players had several deuces in the 12-minute first game, before Williams made a timely response in the following game.
Both sides shared the first eight games of the opening set, before Wang grabbed the chance of wrapping up the set on Williams' forehand flaw.
Williams, seven-time Grand Slam singles winner, built a 3-0 lead early in the second set, but the resilient Wang made a comeback collecting three games in a row.
Wang surrendered her leads in both sets when facing Williams at the same phase last year, but the 91st-ranked Chinese refused to let her chance slip away this time. After the two players shared the next four games for a 5-5 tie, Wang broke Williams' service and recorded her stunning victory over Williams.
Williams suffered a disastrous 35 unforced errors despite notching 28 winners, also inferior to Wang in terms of points on first and second serves.
Wang will next face Croatia's Petra Martic, who eliminated Wang's compatriot Wang Yafan in an earlier match.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
This website uses cookies.