World number one Justine Henin-Hardenne and second seed Jennifer Capriati reached the quarter-finals of the Qatar Open on Wednesday.

Henin-Hardenne, winner of three titles already this year including the Dubai Open last weekend, took some time to settle before defeating Venezuela's Maria Vento-Kabchi 7-5, 6-3. In her second-round match Capriati beat China's Li Ting 7-6, 6-1.

Defending champion Anastasia Myskina of Russia emerged a 6-1, 3-6, 6-1 winner against compatriot and last year's beaten finalist Elena Likhovtseva.

American Meghann Shaughnessy showed the door to world number 10 Ai Sugiyama of Japan, posting a 6-3, 6-2 victory. Lowly-ranked but highly motivated Chinese world number 77, Zheng Jie upset Jelena Dokic 6-4, 6-4.

In Thursday's quarter-finals, top-seed Henin-Hardenne will take on France's Nathalie Dechy while Shaughnessy meets Russia's Svetlana Kuznetsova. Myskina will clash with Zheng and Capriati will cross swords with Silvia Farina Elia of Italy.

Henin-Hardenne had starting problems in her match after Vento-Kabchi broke her in the first and third games to jump to 3-0 lead. But once she settled down on the fast court there was no stopping her.

"I didn't start the way I wanted," the Belgian said. "The court here is different from the one in Dubai. Here it is faster and I needed time to get used to the pace."

Russian duo Myskina and Likhovtseva are vastly improved from last year when they fought out the final. Myskina is more aggressive and powerful while Likhovtseva is sharper.

Myskina said: "Both of us have improved a lot as was evident from the long rallies."

Zheng, ranked 77 in the world, turned pro just over a year ago and posted her best victory to date with the defeat of sixth-seed Dokic.

"I am feeling good. I will remember this victory for the whole of my life," the Chinese said.

Dokic, beaten in the first round in Dubai last week, said: "It was a tight match in the first set. I could have won if I had served better. But somehow I lost my rhythm and I kind of got bogged down there.

"I know that I am going through a slump. It'll take some time for me to start playing well and win matches."

Dokic used to represent Australia but now plays under the flag of Serbia and Montenegro.