CINCINATI: Kim Clijsters kept her comeback rolling, but America’s Williams sisters fell by the wayside at the two million-dollar WTA tournamen.

Former World No 1 Clijsters booked a quarter-final berth with a 6-4, 4-6, 6-2 victory over sixth-seeded French Open champion Svetlana Kuznetsova. The Belgian will play either top seeded Russian Dinara Safina or China’s Peng Shuai in the quarters.

But as Clijsters’ dream return to the courts continued, the day proved a nightmare for both Serena and Venus Williams. Second-seeded Serena, the reigning US Open, Australian Open and Wimbledon champion, was stunned by 29th-ranked Austrian Sybille Bammer 7-5, 6-4. Bammer broke the error-prone Serena three times en route to the victory.

Italian Flavia Penetta, fresh from victory in Los Angeles on Sunday, toppled third-seeded Venus Williams 7-6 (7/2), 6-4. Pennetta will play Slovakian Daniela Hantuchova, who advanced with a 7-6 (8/6), 0-6, 7-6 (7/5) victory over seventh-seeded Vera Zvonareva of Russia.

Fourth-seeded Russian Elena Dementieva, who nabbed Olympic gold in Beijing last year, beat Romanian Sorana Cirstea 6-4, 6-4 to set-up a quarter-final with Danish Caroline Wozniacki. Wozniacki the eighth seed, advanced as Hungary’s Melinda Czink retired injured while trailing 3-0 in the first set.