This week's top-three seeds, led by Venus Williams, all posted quarterfinal victories Thursday at the first-ever Istanbul Cup, a final French Open tuneup. The top-seeded Williams destroyed seventh-seeded Russian Anna Chakvetadze 6-2, 6-1 in a rain-interrupted bout. The former world No. 1 Williams is seeking her first tournament title since last May in Warsaw. Her semifinal opponent on Friday will be little-known Bulgarian qualifier Tszvetana Pironkova, who held off Israeli Shahar Peer 6-3, 7-6 (7-4) on Day 4. The other semi will pit second-seeded Czech Nicole Vaidisova against third- seeded Israeli Anna Smashnova, as the 16-year-old Vaidisova topped fifth- seeded German Anna-Lena Groenefeld 7-5, 7-6 (8-6) and Smashnova dismantled eighth-seeded American Mashona Washington 6-3, 6-1. The winner of this $200,000 event will pocket $30,500.