Sharapova loses to Pennetta in LA semifinals

(CNN) -- Maria Sharapova has been beaten in the semifinals of the LA Championships, losing in three sets to 10th-seeded Italian Flavia Pennetta.

Pennetta earned a final date with Samantha Stosur after defeating Sharapova, who recently returned to action following 10 months on the sidelines with a shoulder injury, 6-2 4-6 6-3.

Three-time grand slam winner Sharapova committed 61 unforced errors and made 16 double faults as she squandered a 3-1 lead in the final set -- allowing Pennetta to claim her first victory over the Russian in three attempts.

"I am very happy," Pennetta told reporters. "It was a difficult match for me because I started well and won the first set 6-2 then I felt a little pressure in the second set because she is a great champion and not easy to beat.

"At 3-1 down I thought it was over but I fought until the end," she added.

Australian doubles specialist Stosur remains on course for his first-ever WTA singles title after storming into the final earlier on Saturday.

The 25-year-old, seeded 13, was too strong for Romanian Sorana-Mihaela Cirstea -- going through 6-3 6-2 in just over an hour.