CHARLESTON, S.C. — Serena Williams extended her winning streak over Maria Sharapova today, advancing to the Family Circle Cup semifinals by beating the Russian 7-5, 4-6, 6-1.

Williams has defeated the fourth-ranked player in the world four straight times since 2005 and is 5-2 overall against Sharapova, who was coming off her first victory on clay last week at Amelia Island. This was their first meeting on clay.

"It was an up-and-down match," said Williams, who is looking for her third tour title this year. "I don't think I played my best. Actually I played far from my best."

She said she wasn't bothered by an ankle she sprained during a match yesterday.

The world's ninth-ranked player faces either Alize Cornet or Agnes Szavay in Saturday's semifinals. Williams' best finish here was runner-up five years ago. That was the same year Sharapova made the field as a 15-year-old qualifier and lost in the first round.

Williams struggled in the first set, which featured several long games. She won one game after it went to deuce seven times.

In the third set, Sharapova won just four points in the first five games.

"I gave it all I had in the first two and I think I ran a little bit short," the Russian said. "My body is adjusting to the clay faster. I'm moving on it a lot better than I used to."

In the evening match, defending champion Jelena Jankovic faces ninth-seeded Vera Zvonareva.

The winner meets either fourth-seeded Elena Dementieva or No. 7 Patty Schnyder in the semifinals of the $1.3 million tournament.