Sam Stosur beat Maria Sharapova 6-4, 7-6 (10) Thursday at the Pan Pacific Open, knocking the two-time champion out to advance to the semifinals.
Stosur broke Sharapova to go up 5-3 in the second set but then lost nine straight points as Sharapova sent the match to a tiebreaker, which Stosur won when Sharapova's return was long.
It was only the second time in 11 matches that Sharapova lost to Stosur, who will face Nadia Petrova of Russia on Friday.
Petrova beat sixth-seeded Sara Errani of Italy 3-6, 7-5, 6-3.
Sharapova wasn't the only top player to bow out. Top-ranked Victoria Azarenka withdrew after a bout of dizziness in her third-round match Wednesday, advancing Angelique Kerber of Germany to the semis.
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