Carlsbad, CA (AHN) - No. 3 seed Anna Chakvetadze beat 2007 Wimbledon champion Venus Williams 6-7 (5), 7-6 (3), 6-2 in the Acura Classic on Friday night and will play top-seeded Maria Sharapova in the semifinal round on Saturday.

Chakvetadze has won three consecutive WTA Tour Events.

Even after blowing a 5-2 lead in the first set, Chakvetadze found enough willpower to withstand everything Williams threw at her.

Chakvetadze overcame eight double faults in the match, three of which gave Williams games in the second set.

Williams, seeded 10th, won the tiebreak after jumping out to leads of 4-0 and 5-3.

As close as the first two sets were, that is how thoroughly the 20-year-old Chakvetadze dominated Williams in the final set.

Chakvetadze's next opponent, Sharapova, defeated India's Sania Mirza 6-2, 6-1 while Switzerland's Patty Schnyder recorded her second straight upset with a 6-4, 6-4 victory over No. 4 seed Nadia Petrova to advance to the other semifinal.

"She's a dangerous opponent with her big serve and her powerful groundstroke,'' the 11th-seeded Schnyder said. "For me, it was still a great win. I never expected to win it that easily.''

Russia's Elena Dementieva, the tournament's No. 9 seed, beat fellow countrywoman Maria Kirilenko 6-2, 6-4 for the right to face Schnyder in the other semifinal.

Dementieva, a two-time Grand Slam runner-up, lost to Schnyder in straight sets at the same tournament in the semifinals last year.

"I've never played against Maria before so I got a little bit nervous in the beginning,'' Dementieva said. "It was a quite difficult match even though the score was easy.''

Schnyder sounded excited about her first appearance in a final in over a year.

"I'm feeling great out on the court,'' she said. "The last three days I know where my shots are going. Everything seems to be working. I just want to keep it up for the weekend.''

Sharapova's victory was similar to her only other match against Mirza a 6-1, 6-1 win at the 2005 U.S. Open.

"I think that from the beginning of the match, I played my game,'' said Sharapova, ranked No. 2 in the world. "I thought I did a really good job of serving well and stepping it up when I had to.''