Eighth-seeded Victoria Azarenka toppled defending champion and second seed Kim Clijsters here on Wednesday to reach the semi-finals of the $9 million WTA and ATP Masters hardcourt tournament.
Azarenka, of Belarus, defeated the ailing Clijsters 6-3, 6-3 to reach her first semi-final of the season.
In the semi-finals she will face third-seeded Russian Vera Zvonareva, a 7-5, 6-3 winner over Poland's Agienszka Radwanska.
Belgium's Clijsters had eight double faults and held her serve just three times in nine service games on Wednesday as she continues to be bothered by a right shoulder injury. The shoulder has bothered her since January when she won the Aussie Open.
Azarenka biggest career win came in 2009 when she captured the Key Biscayne title.
The other semi-final features Russia's Maria Sharapova squaring off against rising German star Andrea Petrovic.