Stanford : India's Sania Mirza has ensured her semi-final ticket for the $600,000 Bank of the West Classic tournament with a straight-sets victory over Patty Schnyder of Switzerland.
Unseeded Mirza downed fourth-seeded Schnyder 7-6 (7-2) 6-1 for her second straight upset this week, reported Fox Sports on its website.
She bounced sixth-seeded Tatiana Golovin of France in the second round.
Mirza will clash with eighth-seed Austrian Sybille Bammer in a semi final.
The Indian's victory over world No.19 Golovin was her first over a top-20 player since she was sidelined by a knee injury in March.
Sania is now aiming to add one more to her Women's Tennis Association (WTA) Tour title, which she claimed at Hyderabad in 2005.
Top-seeded Russian Anna Chakvetadze booked her semi-final place, rallying to defeat seventh-seeded Katarina Srebotnik of Slovenia 4-6 6-2 6-2.
Chakvetadze has now won seven consecutive hard court matches and is in a position to capture her second singles title in as many weeks.