Australian Samantha Stosur is through to the quarter-finals of the Dubai Tennis Championships after a tough three-set win over Czech Lucie Safarova.

Stosur saved nine break points in the match to never lose her serve against the feisty Czech, eventually winning 6-1 6-7 (5-7) 6-1 in just over two hours.

Awaiting Stosur in the last eight is Serbian and eighth seed Jelena Jankovic, who easily beat Italy's Flavia Pennetta 6-4 6-2.

Caroline Wozniacki eased into the last with a convincing 6-2 6-3 victory against Romanian Simona Halep.

The 21-year-old served at 77 percent for the encounter and broke five times against Halep, who is ranked 53 in the world.

World number four Wozniacki will meet Ana Ivanovic in the last eight after the Serbian edged past Russian Maria Kirilenko 6-2 7-6 (7-4).

Earlier in the day, Azarenka pulled out of the WTA Premier event because of an ankle injury sustained in Doha last week.

The Belarusian world number one, who is on a 17-match unbeaten run to start the season, joins Wimbledon champion Petra Kvitova on the sidelines after the Czech withdrew because of a virus.

Lucky loser Casey Dellacqua replaced Azarenka in the draw, but the Australian was unable to capitalise as she was thrashed 6-0 6-2 by German Julia Goerges in 44 minutes.

Goerges lost just nine points when serving as she easily disposed of the world number 102.

Daniela Hantuchova will face Goerges in the quarter-finals after the Slovakian comfortably overcame China's Peng Shuai 7-5 6-2.

In other matches, fifth seed Agnieszka Radwanska easily got past wildcard Shahar Peer 7-5 6-4 and ninth seed Sabine Lisicki beat qualifier Iveta Benesova 6-3 6-3.