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Top-seeded and defending champion Victoria Azarenka, Serena Williams and two-time Doha titlist Maria Sharapova were among Thursday's third-round winners at the $2.369 million Qatar Open.

The world No. 1 and reigning two-time Australian Open titlist Azarenka dismantled young American Christina McHale 6-0, 6-0 in 67 minutes on the hardcourts at Khalifa International Tennis Complex.

Azarenka, who beat former U.S. Open champion Sam Stosur in last year's Doha finale, will face sixth-seeded French Open runner-up Sara Errani in Friday's quarterfinals.

Meanwhile, the reigning Wimbledon and U.S. Open champion Williams handled Poland's Urszula Radwanska 6-0, 6-3 in 57 minutes and the third- seeded French Open champion Sharapova cruised past Czech veteran Klara Zakopalova 6-3, 6-3 on Day 4.

The 31-year-old Williams is now one win away from becoming the oldest-ever top-ranked women's player. If she reaches the semifinals she will return to No. 1 for the first time in 2 1/2 years. Chris Evert held the top ranking in 1985 while just shy of her 31st birthday.

"It's awesome," Williams said. "Since I didn't do the youngest, I figure I'll do the oldest."

If Williams fails to reach the semis, then Azarenka can keep top spot by reaching the Doha final. Sharapova can pass both players if she titles this week and Williams and Azarenka lose on Friday.

Also on Thursday, fourth-seeded Wimbledon runner-up Agnieszka Radwanska got past 13th-seeed former world No. 1 Ana Ivanovic 6-1, 7-6 (8-6); the aforementioned Errani outlasted Slovak Daniela Hantuchova 7-5, 5-7, 6-2 in 2 hours, 37 minutes; seventh-seeded former Wimbledon champion Petra Kvitova overcame 11th-seeded Russian and 2006 Doha champion Nadia Petrova 4-6, 6-4, 6-3; an eighth-seeded Stosur straight-setted two-time Doha runner-up Svetlana Kuznetsova 6-4, 7-5; and 10th-seeded former No. 1 and 2011 Doha runner-up Caroline Wozniacki cooled off rising German Mona Barthel 7-6 (8-6), 6-3. Barthel was a titlist in Paris two weeks ago.

Eight of the top-11 players in the world saw action on Thursday.

Friday's other marquee quarters will pit Williams against Kvitova, Sharapova versus Stosur and Radwanska against Wozniacki.

The 2013 Qatar Open winner will claim $426,000.