Justine Henin was made to work very hard to preserve her record

The top-seeded Belgian surrendered a tense second set before closing out a 7-5 6-7 (6-8) 6-3 victory.

"That's the kind of match I need," said Henin after making the quarter-finals.

"It's never easy to have a bye and play a girl that has played a few matches. In the third set I felt the best I've felt in the last few weeks."

Third-seeded Serb Ana Ivanovic showed no sign of her recent ankle injury as she defeated Czech Nicole Vaidisova 6-4 6-0.

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And Amelie Mauresmo will meet second seed Svetlana Kuznetsova in the quarter-finals after beating Japan's Akiko Morigami 4-6 6-1 6-4 in Dubai.

Mauresmo, who has slipped to 29th in the world rankings, is looking to reach her first semi-final since June but she faces a tough test against Kuznetsova.

The Russian world number two thrashed Lucie Safarova 6-1 6-2.

Despite her playing well and hitting the ball very solid I was also just struggling with my game Jelena Jankovic

Fourth seed Jelena Jankovic needed more than two hours to see off India's Sania Mirza 4-6 6-3 6-4.

Mirza led 3-1 in the final set and had three points to make it 5-3 before Jankovic prevailed.

"She gave me a hard time on the court," said Jankovic.

"Despite her playing well and hitting the ball very solid I was also just struggling with my game."