Mason, OH (SportsNetwork.com) - No. 1 seed Serena Williams won two tiebreakers to outlast Samantha Stosur in the second round of the $2.5 million Western & Southern Open on Wednesday.
Williams came away with a 7-6 (9-7), 7-6 (9-7) win, defeating the Australian for the eighth time in their 11 all-time meetings.
She moved on to face 13th-seeded Flavia Pennetta, who beat American qualifier Taylor Townsend, 6-4, 6-3.
American Sloane Stephens won, topping Barbora Zahlavova Strycova in straight sets to set up a meeting with No. 8 seed Jelena Jankovic, who ousted Annika Beck in a second-set tiebreaker.
Another American, wild card Christine McHale, won just four games in a loss to ninth-seeded Ana Ivanovic, who will meet Svetlana Kuznetsova after Kuznetsova outlasted seventh-seeded Canadian Eugenie Bouchard in three sets.
Third-seeded Petra Kvitova was upset by Elina Svitolina in straight sets and fourth-seeded Agnieszka Radwanska lost just four games in a win over Kurumi Nara.
Svitolina will play No. 15 seed Carla Suarez Navarro, a straight-set winner over Pauline Parmentier; and Radwanska draws Sabine Lisicki, who knocked off No. 14 seed Sara Errani in three sets.
Sixteenth-seeded Lucie Safarova will face No. 2 seed Simona Halep after a win over Zarina Diyas in straight sets, and Anastasia Pavlyuchenkova gets No. 5 seed Maria Sharapova in the third round after beating Karin Knapp, also in two sets.