CHARLESTON, South Carolina: Second seed and defending champion Samantha Stosur crashed out of the WTA's Family Circle Cup Thursday, falling in straight sets to unseeded Russian Elena Vesnina.
On a day when top-seeded Caroline Wozniacki passed a tough test with flying colors, coming up with two tiebreak victories to reach the quarter-finals, Australia's Stosur fell 6-4, 6-1 to Vesnina.
World No. 1 Wozniacki, meanwhile, fended off the solid challenge of Czech Barbora Zahlavova Strycova, 7-6 (8/6), 7-6 (11/9) in a match lasting more than 2 1/2 hours.
Wozniacki jumped out to a 4-1 first-set lead.
But after a frustrated Zahlavova Strycova spoke to her coach, she adopted a more aggressive approach that paid handsome dividends.
The Czech was able to extend the rallies, pushing Wozniacki into the corners of the court to chase down shots.
After forcing the first tiebreaker, Zahlavova Strycova dropped behind 5-1, then won five straight points to hold a set point that she couldn't convert.
Zahlavova Strycova took a 2-0 lead in the second frame before Wozniacki rallied.
After forcing the tiebreaker, Wozniacki took a 5-2 lead, but Zahlavova Strycova fought off four match points.
Zahlavova Strycova had a set point at 9-8, but again couldn't convert, this time surrendering the match.
Despite the defeat, Zahlavova Strycova said was proud of her performance.
In the quarter-finals, Wozniacki will play sixth-seeded Yanina Wickmayer of Belgium, a 6-4, 7-5 winner over Georgia's Anna Tatishvili.
Vesnina next plays Germany's Julia Goerges, who beat fifth-seeded Israeli Shahar Peer 6-2, 6-3.
Third-seeded Jelena Jankovic of Serbia defeated South African Chanelle Scheepers 6-2, 6-2 to reach the quarter-finals.
She'll face 18-year-old American Christina McHale, who beat Slovakian Daniela Hantuchova 7-6 (7/3), 6-1.
The other quarter-final will pit China's Peng Shuai against India's Sania Mirza.
Peng defeated seventh-seeded Russian Nadia Petrova 6-3, 5-7, 6-2, while Mirza beat Germany's Sabine Lisicki 6-4, 6-4.
