Stanford, CA -- (Sports Network) - Serena Williams breezed past Patty Schnyder in straight sets to move into the semifinals, while defending champion Anna Chakvetadze lost Friday at the $600,000 Bank of the West Classic tennis event.

The top-seeded Williams beat the fifth-seeded Swiss Schnyder 6-3, 6-1, and reached the final four in her first appearance at this tournament on the hardcourts at Taube Family Tennis Stadium.

Williams, last month's Wimbledon runner-up to her older sister Venus, will face Aleksandra Wozniak in the semifinals. The Canadian Wozniak, who is also making her tournament debut, bested Australian Samantha Stosur 6-2, 5-7, 6-4.

Meanwhile, second-seeded Chakvetadze dropped a 6-3, 6-4 decision to sixth- seeded Marion Bartoli. The Russian Chakvetadze beat India's Sania Mirza in last year's finale, but was erratic on Friday, keeping only 54 percent of her first serves in play.

The match lasted one hour, 20 minutes, and put Bartoli into the semifinals of this tournament for the first time. This is Bartoli's sixth appearance at this tournament, but the Frenchwoman had only reached the second round on four previous occasions.

Bartoli will face Japanese veteran Ai Sugiyama, who reached the semifinals by besting Slovakian Dominika Cibulkova 6-7 (4-7), 7-6 (7-5), 5-3. Cibulkova retired nearing the finish line, as Sugiyama reached her first singles semifinal this year.

The 2008 Stanford titlist will collect $95,500.