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 quarterfinals, 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 21/2 hours. In the quarterfinals, Wozniacki will play sixth-seeded Yanina Wickmayer of Belgium, a 6-4, 7-5 winner over Georgia's Anna Tatishvili. Vesnina next plays play 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 quarterfinals. She'll face 18-year-old American Christina McHale, who beat Slovakian Daniela Hantuchova 7-6 (7-3), 6-1. The other quarterfinal will pit China's Peng Shuai against Indiana'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. Fish advances In Houston, Mardy Fish made a victorious debut as America's top-ranked men's tennis player Thursday, defeating Albert Ramos in straight sets 6-3, 6-4 to reach the quarterfinals of the US Clay Court Championships. Fish will face sixth-seeded Kei Nishikori of Japan Friday. Nishikori beat Igor Andreev of Russia 6-3, 6-3. Third-seeded Guillermo Garcia-Lopez of Spain also reached the quarterfinals, overcoming five double-faults in a 6-4, 6-1 victory over India's Somdev Devvarman. Seventh-seeded Pablo Cuevas of Uruguay cruised to a 7-5, 6-1 victory over American James Blake. Cuevas, who defeated Roddick in Miami, had six aces as he dominated the second set. Azarenka advances In Spain, top-seeded Victoria Azarenka reached the semifinals of the Andalucia Tennis Experience after Dinara Safina retired with an injury while trailing 5-1. Azarenka will next face eighth-seeded Sara Errani after the Italian beat Alexandra Dulgheru of Romania 6-2, 6-2. Svetlana Kuznetsova easily advanced by beating Lara Arruabarrena-Vecino 6-1, 6-2. The second-seeded Russian plays Irina-Camelia Begu of Romania, who defeated Klara Zakopalova 6-3, 6-3. Montanes in last four In Morocco, top-seeded Albert Montanes of Spain defeated Fabio Fognini of Italy 7-6 (1), 6-1 Friday to reach the semifinals of the Grand Prix Hassan II. Montanes next meets fellow Spaniard Pablo Andujar, who advanced with a 6-2, 6-2 win over another Spaniard Pere Riba. Fifth-seeded Potito Starace of Italy upset No.3 Gilles Simon 6-4, 3-6, 6-4 and will face either Victor Hanescu or qualifier Andrey Kuznetsov in the other semifinal at the clay-court tournament.