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 in Stanford 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.