BEIJING, Oct. 7 (UPI) -- Flavia Pennetta defeated world No. 1 Caroline Wozniacki in three sets Friday in the quarterfinals at the China Open tennis tournament in Beijing.
Pennetta was 0-5 lifetime against Wozniacki before Friday but piled up eight service breaks in a 3-6, 6-0, 7-6 (7-2) victory. The loss marked the second time in as many weeks Wozniacki was unable to defend a tournament title. She lost in the Round of 16 in Tokyo last week.
Even though she won the first set, Wozniacki dropped serve twice and then won just one-third of the points in the second-set shutout. Each player lost serve three times in the third set but Pennetta controlled the tiebreaker to advance.
That result left No. 9 Andrea Petkovic the highest seed in the draw. Petkovic was a 6-3, 7-6 (7-2) winner over 12th-seeed Anastasia Pavlyuchenkova. Petkovic had five breaks in 10 receiving games.
Also Friday, 11th-seeded Agnieszka Radwanska built a 6-3, 3-2 lead over Ana Ivanovic when Ivanovic was unable to continue because of a back injury. Qualifier Monica Niculescu took the fourth semifinal spot with a 3-6, 6-3, 6-4 win over Maria Kirilenko.
Pennetta draws Radwanska in Saturday's semifinals with Niculescu and Petkovic meeting in the other.