Duan won 57 percent of the points when Date-Krumm served during a 6-3, 6-2 first-round win. She dropped her own serve three times but was 3-for-5 in each set in converting break chances to gain the second round.
No. 2-seeded Yanina Wickmayer defeated Yaroslava Shvedova 7-5, 6-2. Wickmayer fought off six of the seven break points she faced and Shvedova hurt her own chances by committing 12 double faults.
Zhang Shuai, the third seed, routed Nicha Lertpitaksinchai 6-3, 6-0. Zhang fired off seven aces and won nearly three-quarters of the points on serve. She held Lertpitaksinchai to 16 points in the second set.
Fourth-seeded Ayumi Morita topped Olga Savchuk 6-2, 6-4 by winning half the points when Savchuk served and No. 6-seeded Misaki Doi survived a 2 1/2-hour battle against Xu Yi-Fan 6-2, 6-7 (5-7), 6-4.
Petra Martic completed a 6-0, 6-0 shutout of Vera Dushevina in 57 minutes. Martic won nearly two-thirds of the points on the day.
Wang Qiang defeated Stephanie Dubois 6-4, 6-4; Jarmila Gajdosova was a 6-2, 6-4 winner over Peangtarn Plipuech; Julia Glushko beat Zhang Yuxuan 4-6, 6-1, 6-1; and Wang Yafan got by Sun Ziyue 3-6, 6-3, 6-2 in other first-round matches.