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Four-time runner-up Maria Sharapova secured a semifinal berth at the $4.195 million Sony Open tennis event.

The second-seeded former world No. 1 straight-setted eighth-seeded Italian Sara Errani 7-5, 7-5 in 2 hours, 29 minutes in a rematch of last year's French Open final, which was also won by the tall Russian superstar.

Sharapova popped six aces and broke Errani six times on Day 9 of this 13-day tournament and is now 4-0 lifetime against the gritty Italian. The Russian, however, also had 57 unforced errors, including 13 double faults.

"I made things much more difficult than they should have been," Sharapova said. "It's nice to get through a match when you don't feel like you're playing your best, because you feel like you have a lot to improve.

"Would I have loved to play better? Of course. But some days you can't go out on the court and everything goes in and you feel great and you're playing the way you imagined to play. It just doesn't happen."

The hot Sharapova is currently riding a 10-match winning streak, which includes a title at Indian Wells two weeks ago and a quarterfinal victory over Errani in the California desert.

The career Grand Slam winner Sharapova lost to Polish star Agnieszka Radwanska in last year's Sony Open finale and was also the runner-up here two years ago.

Sharapova will meet Serbian Jelena Jankovic in the semifinals Thursday on the hardcourts at Crandon Park. The 22nd-seeded Jankovic outlasted 15th-seeded Italian Roberta Vinci 6-4, 6-7 (6-8), 6-3.

The former No. 1 Jankovic was a Key Biscayne runner-up back in 2008.

Thursday's other semifinal will pit top-seeded and five-time champion Serena Williams against a fourth-seeded Radwanska.

The reigning Wimbledon and U.S. Open champion Williams is 59-7 lifetime at this event and tied with the legendary Steffi Graf for the most wins in Key Biscayne.

The mighty Williams has appeared in seven Sony Open finals, including three straight titles from 2002-04 and back-to-back championships in 2007 and 2008.