Wang, No 186 in the world, won the final five games in beating Wozniacki 2-6, 7-6 (7-1), 6-1. Wang won two-thirds of the points once the match hit the second-set tiebreaker.
Wozniacki won just more than half of the points on serve and faced 19 break points. Wang was able to finish five of those, including two in the final five-game run to win the match.
Wang was part of a banner day for qualifiers in the tournament as they went 5-1 Wednesday. That success includes Zarina Diyas' 6-7 (5-7), 6-1, 7-5 win over No. 8-seeded Kristyna Pliskova. Diyas dropped serve just once and didn't face a break point in the decisive third set.
Other qualifiers who advanced Wednesday were Nudnida Luangnam, Luksika Kumkhum and Akgul Amanmuradova.
Rain, which stopped play Monday and Tuesday, hit late, causing a suspension in Wednesday's final match in which second-seeded Hsieh Su-wei, the tournament's defending champion, was playing Kurumi Nara. Nara had a 2-1 lead in the first set with Hsieh about to serve when play was halted.
Also Wednesday, third-seeded Anastasia Pavlyuchenkova edged Vera Dushevina 2-6, 6-3, 7-6 (8-6) and No. 4-seeded Ayumi Morita won more than 60 percent of the points in a 6-1, 6-1 romp over Cagla Buyukakcay. Eleni Daniilidou, the No. 7 seed, won in three sets.
Other with first-round winners Wednesday were Zhang Shuai, Ashleigh Barty and Duan Ying-Ying.