Stanford, CA -- (Sports Network) - Seventh-seeded Russian Nadia Petrova came up an opening-round loser Tuesday at the $600,000 Bank of the West Classic tennis event.

Promising Slovakian Dominika Cibulkova doused Petrova in 6-4, 3-6, 6-3 fashion at Taube Family Tennis Stadium.

Fifth-seeded Swiss Patty Schnyder had no problems handling American Amber Liu in straight sets 6-1, 6-1.

Another upset on Tuesday happened when Canadian qualifier Aleksandra Wozniak bounced back from a first-set loss to down eighth-seeded Italian Francesca Schiavone 2-6, 6-3, 6-2.

In other opening-round play, Aussie lucky-loser Samantha Stosur stopped Russian Anastasia Rodionova 6-3, 6-1; Portuguese Michelle Larcher de Brito dismissed Argentine Gisela Dulko 7-5, 7-6 (7-1); Israeli Shahar Peer drove out Hungarian Melinda Czink 7-5, 6-0; and Great Britian's Anne Keothavong knocked off India's Sania Mirza 7-6 (7-4), 6-1.

Anna Chakvetadze is the defending champion, having bested Mirza in last year's finale. The top seeds here are Wimbledon runner-up Serena Williams and Chakvetadze.

The 2008 Stanford titlist will collect $95,500.