The victory sets up a quarterfinal match for Ivanovic against Wimbledon champion and eighth-seeded American Venus Williams, who beat Marta Domachowska of Poland 6-4, 6-4 Monday.
Henin, the tournament's 2004 champion, stretched her winning streak to 32 matches, ousting Taiwan's Su-Wei Hsieh 6-6, 6-2. The reigning French and U.S. Open winner from Belgium next meets the fifth-seeded Sharapova, who downed Elena Dementia 6-2, 6-0 in a match that lasted 62 minutes.
Williams, the No. 7 seed, beat Nicole Vaidisova 6-3-6-4. The American player is on the same side of the draw as Henin and Sharapova, her opponent in last year's final.
Henin said she's expecting a battle with Sharapova.
"I always know to beat her I have to be at my best," Henin said "She's a real fighter. She never gives up."
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