CARSON, California (AP) – Maria Sharapova overcame problems with her new service motion to outlast Urszula Radwanska on Friday and book a place in the semifinals of the L.A. Women's Tennis Championships.

Sharapova beat the eighth-seeded Pole 6-4, 7-5 to set up a semi against either second-seeded Russian compatriot Vera Zvonareva or tenth-seeded Flavia Pennetta of Italy, who were to play later Friday.

In other quarterfinals, 13th-seeded Australian Samantha Stosur beat China's Zheng Jie, seeded 14th, 4-6, 6-3, 6-4. Stosur's semifinal opponent will be Romania's Sorana Cirstea, who beat Agnieszka Radwanska – Urszula’s sister – 7-6 (4), 1-6, 7-5.

Sharapova, still finding her way after shoulder surgery that sidelined her for nearly 10 months, is working on an abbreviated service motion to take pressure off the joint.

“I made a lot more errors than I wanted to. In the second set, just kind of went off,” she said. “I created so many bad habits. Eventually it’s going to work itself into place.”

Sharapova struggled to control it in the second set, when she held serve just twice. She gained her first hold to tie the set at 5-5. The Russian broke Radwanska in the next game, then served out the match.

Sharapova’s second serve ace set up match point. Her forehand winner in the corner was called long, but she successfully challenged the call to win the match.

Sharapova has yet to win the title in Carson, where she gained the world’s No. 1 ranking during the tournament in 2005. She returned to singles play in May and came into this week ranked 61st.
Stosur, regarded chiefly as one of the world’s top doubles players, has enjoyed a strong run in singles the past few months, reaching a career-best ranking of 18th in June. She has yet to win a singles title on the WTA Tour, although she's been a four-time runner-up, including once last year.
“It’s definitely a goal of mine to try and win a singles title.

I’ve been in four finals and lost every one of them in three sets,” she said. “My whole career I've been trying to become a better singles player. This year it's all just come together.”

A week ago, Stosur defeated Serena Williams in three sets before losing to eventual winner Marion Bartoli in the semifinals at Stanford.

She beat then-No. 2 Dinara Safina in the quarterfinals at Miami in March and reached the French Open semis in June.