Stosur, seeded seventh, was defeated by Sofia Arvidsson 7-6 (7-4), 7-5, Arvidsson won two of four break chances in each set. She did lose her own serve three times but in general had a solid service game, winning two-thirds of the points on serve.
Ksenia Pervak outlasted Wozniacki, the No. 8 seed, 2-6, 6-3, 7-6 (7-1) in a match that took 2 hours, 48 minutes. Pervak won just one more point (50-49) serving over the course of the match but claimed 60 percent of the points on serve in the third set.
No. 4-seeded Angelique Kerber came away with a 6-2, 4-6, 6-2 win over Anna Tatishvili. Kerber lost her serve just once outside of the second set when she was broken three times, and finished off seven of her 19 break-point opportunities.
Fifth-seeded Sara Errani cruised to a 6-1, 6-3 win over Olga Puchkova, winning 60 percent of the points in the match. She lost serve twice in the second set but still won 57 percent of the points.
Other first-round results included Sabine Lisicki racing past Lucie Safarova 6-2, 6-4 and Alize Cornet coming back for a 2-6, 6-3, 6-1 decision over Bojana Bobusic. Also, qualifier Monica Puig defeated Olivia Rogowska 6-2, 6-3 and Sloane Stephens beat Dominika Cibulkova 6-2, 6-3.