The fifth-seeded Sharapova had to rally from a first-set loss, eventually prevailing over third-seeded Pole Agnieszka Radwanska 1-6, 6-2, 6-2 at Taube Family Tennis Stadium on the Stanford University campus.
In Saturday's other semifinal, Azarenka of Belarus marked her 21st birthday by upsetting top-seeded Australian Samantha Stosur in straight sets 6-2, 6-3.
Sharapova has won two of three all-time matches between the pair. The Russian will be looking for her 23rd career title and third of the year while Azarenka is seeking her fourth championship and first of the year.
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