Stanford (California):Serena Williams, still trying to put the sting of her Wimbledon final defeat behind her, reached the semi-finals of the 600,000-dollar WTA hardcourt tournament on Friday.
The top-seeded American, playing in Stanford for the first time, punched her ticket to the final four with a 6-3, 6-1 quarter-final victory over fifth-seeded Swiss Patty Schnyder.
The tournament is Williams's first since falling in the Wimbledon final to elder sister Venus earlier his month.
Although she hasn't won a Grand Slam title since the 2007 Australian Open, Serena has put together an impressive season with three championships and a 33-4 record.
The 26-year-old has reached the quarter-finals or better at eight of nine events she has entered, with her only defeat before the round of eight coming against Katarina Srebotnik in the third round of the French Open.
While Williams is new to the tournament, Schnyder boasts a runner-up finish in 2006, a semi-final appearance in 2005 and quarter-final spots in 2004 and last year.
However, the Swiss veteran's struggles against Williams -who has now won eight of their 11 contests - continued.
Williams next faces Candian Aleksandra Wozniak, who beat Australian Samantha Stosur 6-2, 5-7, 6-4.
Wozniak had beaten Stosur in straight sets in the final round of qualifying on Monday, but Stosur was awarded a place in the main draw as a lucky loser when American Lindsay Davenport withdrew with a knee injury.
Wozniak, 20, made the most of her first quarter-final of the season, and now will vie to reach her first WTA final since last season at Fes.
In other quarter-final matches, Japanese veteran Ai Sugiyama advanced after 19-year-old Slovakian Dominika Cibulkova was forced to retire with a left leg cramp.
Sugiyama battled back from the brink of defeat, saving three match points in the second set, and was leading 6-7 (4/7), 7-6 (7/5), 5-3, when the match was halted.
Sugiyama will face sixth-seeded Marion Bartoli of France, who upset second seed and defending champion Anna Chakvetadze of Russia 6-3, 6-4.
Chakvetadze, 21, had hoped a move to the US hardcourts would help turn around a so-far disappointing season.
Last year she won this tier 2 event, as well as in Cincinnati, and reached the semi-finals at San Diego and the US Open.
Ranked eighth in the world, she has won one title this season, but reached te semi-finals just once in 10 events since.
Bartoli, too, arrived in the States for the build up to the US Open seeking consistency.
The 2007 Wimbledon finalist and world No. 15 has yet to appear in a final this year.