The native of Poprad, Slovakia, the tournament's third seed, was beaten 6-0, 6-2, by unseeded German Sabine Lisicki.
Second-seeded Anna Chakvetadze of Russia lost 6-2, 6-4 in her match against Czech Iveta Benesova.
Elsewhere, former world No. 1 Amelie Mauresmo, the fifth seed, outlasted Germany's Stephanie Gehrlein 6-2, 3-6, 6-0; fourth-seeded Dane Caroline Wozniacki topped China's Peng Shuai 6-4, 6-4; No. 6 seed Li Na of China beat Ukrainian Mariya Koryttseva 7-6 (8-6), 6-3; Romanian Sorana Cirstea downed Italy's Sara Errani 6-4, 6-2; seventh-seeded Anabel Medina Garrigues pasted fellow Spaniard Virginia Ruano Pascual 6-2, 6-1; and Germany's Anna-Lena Groenefeld topped Belgian Yanina Wickmayer 7-5, 6-4.
Thursday's quarterfinal matches are top seeded Elena Dementieva-Gisela Dulko; Mauresmo-Groenefeld; Na-Benesova; and Cirstea-Hantuchova.
The eventual champion will claim a $35,000 winner's check on Sunday.
Workers accuse National Zoo of animal mismanagement
Couple calls 9-1-1 over missing hash browns; assault McDonanld's employees