Former champion Maria Sharapova was a hard-fought quarterfinal winner Wednesday at the U.S. Open.

The third-seeded former world No. 1 overcame 11th-seeded Frenchwoman Marion Bartoli 3-6, 6-3, 6-4, over two days at Ashe Stadium.

Sharapova will face current world No. 1 Victoria Azarenka in a semifinal here on Thursday. Azarenka beat Sharapova in this year's Australian Open finale and is 5-4 lifetime against the Russian superstar, including a 2-1 record, all in finals, in 2012.

The Sharapova-Bartoli match was suspended because of rain in New York on Tuesday, with the 2007 Wimbledon runner-up Bartoli up a pair of breaks at 4-0 in the first set.

The resumption of the bout was then delayed by rain on Wednesday at the USTA Billie Jean King National Tennis Center.

Bartoli would return to finish off a first-set win, despite losing three-of- five games in the stanza on Day 10 of the fortnight.

Sharapova then answered by taking the second set to set the stage for a tight third.

The tall Russian got the key service break she needed for a 5-4 lead in the final set and closed out the match on her serve in the next game. Sharapova set-up her first match point with a resounding ace and closed out the match when Bartoli misfired wide with one final return.

"I think that rain break gave me a few hours to think about things," Sharapova said. "I came out so flat yesterday; she came out on fire. She's so tough."

Sharapova improved to 12-0 in three-set matches this year, advancing in 2 hours, 32 minutes with the help of 10 aces, although she did commit 11 double faults.

She secured a berth in her 15th career Grand Slam semifinal and her first U.S. Open semi in six years.

The 25-year-old Sharapova completed a career Grand Slam by capturing the French Open in June and lost to Serena Williams in the gold-medal match at the London Olympic Games last month. She won her lone U.S. Open title back in 2006.

Also on Wednesday, an all-Italian quarterfinal saw 10th-seeded French Open runner-up Sara Errani handle 20th-seeded good friend and doubles partner Roberta Vinci 6-2, 6-4. Errani and Vinci are into the doubles semifinals together in Flushing.

The 25-year-old Errani will meet the Williams-Ana Ivanovic winner on Thursday. The gritty Italian has reached at least the semis at two of the four majors this year and was a quarterfinalist at the Aussie Open in January.

Errani lost to Sharapova in the French Open final.

The fourth-seeded Williams owns 14 major singles titles, including this year's Wimbledon championship and a trio of U.S. Open crowns. She lost to Sam Stosur in last year's U.S. Open finale.

The 12th-seeded Ivanovic, like Williams, is a former world No. 1 and former French Open champ.

Williams is 3-0 lifetime against Ivanovic, including 2-0 at the U.S. Open, where the American great beat the Serb in the fourth round a year ago.