Babos, seeded No. 1, defeated Zhu Lin 6-4, 6-4 while winning nearly 70 percent of the points on serve. She did lose the two break points she faced but also cashed in four break chances of her own.
Doi, the second seed, took more than 70 percent of the points when serving and beat Wang Yafan 6-0, 6-2. She lost 13 points overall in the first set and a total of 10 points in her seven games on serve.
Eri Hozumi won the first set 6-2 and fifth-seeded Duan Ying-Ying was unable to play in the second and retired while Zheng Saisai eliminated eighth-seeded Alize Lim 6-2, 6-3. Zheng took 58 percent of the points when serving and 55 percent off Lim's serve.
No. 6-seeded Zhou Yi-Miao rolled past Yurika Sema 6-2, 6-1 in just more than an hour. Zhou converted six of her seven break opportunities.
Other results Tuesday saw Michaela Honcova stop Zhang Yuxuan 3-6, 6-4, 6-4 in the only match of the day to go three sets; Michaella Krajicek advance over Erika Sema (Yurika Sema's sister) 6-2, 6-4; Hu Yue-Yue oust Peangtarn Plipuech 6-1, 6-4; and Xu Yi-Fan take a 6-1, 3-0 decision after Wen Xin retired.