Wimbledon champion Serena Williams notched a convincing win over South African Chanelle Scheppers on Friday to advance to the semifinals, while second-seeded Frenchwoman Marion Bartoli was sent packing by Belgian Yanina Wickmayer at the $740,000 Bank of the West Classic.

The younger Williams sister needed just one hour, 13 minutes to polish off a 6-4, 6-0 victory over Scheppers on the hardcourts at Stanford's Taube Family Tennis Stadium.

Williams won 69 percent of first-serve points, fired eight aces and saved 7- of-9 break points in the victory.

Wickmayer dispatched Bartoli, 6-3, 6-2 in one hour, 20 minutes and won 73 percent of first-serve points. Bartoli largely was her own worst enemy on Friday as she saved only 3-of-9 break points and double-faulted nine times en route to the quarterfinal exit.

Williams beat Bartoli in last year's Stanford finale. Bartoli was the champion here three years ago and was also a Bank of the West runner-up in 2008.

American lucky-loser Coco Vandeweghe secured a spot in the final four by handling Poland's Urszula Radwanska 6-4, 6-4. The 20-year-old Vandeweghe is the niece of former NBA player, head coach and general manager Kiki Vandeweghe. Radwanska is the younger sister of world No. 2 Wimbledon runner-up Agnieszka Radwanska.

Romania-native Sorana Cirstea also secured a spot in the semifinals with a 6-7 (5-7), 6-2, 6-0 victory over Dominika Cibulkova. Cirstea converted 52 percent of her serves and fired 15 aces in the two-hour triumph.

Vandeweghe will face Wickmayer, while the top-seeded Williams will battle nine-seed Cirstea for a spot in Sunday's final.

The winner of the Bank of the West Classic will pocket $96,000.