(CNN) -- Maria Sharapova took a step closer to her first tournament victory since January 2008 as she moved into the semifinals of the L.A. Women's Tennis Championships on Friday night.
Maria Sharapova is seeking to win her 20th title on the WTA Tour with victory in Los Angeles.
The former world No. 1, who has slumped to 61st in the rankings after nine months out with shoulder problems, beat Poland's Urszula Radwanska 6-4 7-5 to set up a last-four clash with last year's losing finalist Flavia Pennetta.
The Russian, whose last of 19 titles on the WTA Tour was at the 2008 Australian Open, had to battle against the unseeded 18-year-old as she continued to struggle with her new modified serve.
Sharapova earned the only break of the first set, winning the third game in an 18-point epic, and fought back from 5-3 down in the second set.
"It was just a matter of regrouping and staying positive," the 22-year-old told the WTA Tour's official Web site. "Slowly but surely, I'm finding my way on the court.
"A lot of what you lose when you miss time is that reflex, that hand-eye coordination, and I feel I'm getting it back. Sometimes it's just a matter of inches. There's a very thin line between winning and losing a tennis match."
Sharapova next faces a 10th seed who has knocked out her higher-ranked fellow Russians in the past two days, with the Italian following up her victory over fifth seed Nadia Petrova by upsetting second seed Vera Zvonareva on Friday.
Pennetta triumphed 6-4 6-2 to notch her ninth successive victory after winning the Palermo event, giving her a 10th win against top-10 players this season.
"I was playing very well from the beginning. My serve was great tonight and that was the important thing for me," said Pennetta, who has lost both her previous clashes with Sharapova -- the last being at Wimbledon in 2006.
"It will be a tough match against Maria. I will need to play like I did tonight. My serve needs to be there again."
In the other semifinal, in-form 13th seed Samantha Stosur will take on unseeded Romanian Sorana Cirstea.
The Australian, who reached the semifinals in Stanford after knocking out world No. 2 Serena Williams, ousted Chinese 14th seed Zheng Jie 4-6 6-3 6-4.
Zheng, who knocked out world No. 1 Dinara Safina in the previous round, had led 3-1 in the second set but was unable to maintain her momentum.
Cirstea made it a miserable day for the Radwanska family, upsetting Urszula's eighth-seeded older sister Agnieszka 7-6 (7-4) 1-6 7-5.
The 18-year-old earned revenge for her crushing 6-0 6-1 defeat by the Pole in the first round at Stanford.
It's a big difference from last week when I played her," Cirstea said. "I had to fight a lot at the end.
"When she was serving for the match at 5-4 in the third set, I was just focused on staying in the match. I was patient today, that's why I won."