Sania Mirza and her partner Chia-Jung Chuang of Chinese Taipei have upset second seeded Spanish pair of Anabel Medina Garrigues and Virginia Ruano Pascual to enter the women's doubles quarterfinal of the Madrid Open event.

The Indo-Chnise Taipei pair won 7-6 (4), 4-6, 10-7 and will take on Victoria Azarenka of Belarus and Elena Vesnina of Russia in the last eight round of the $ 4,500,000 event.

Azarenka and Vesnina whistled past Russian duo of Alla Kudryavtseva and Ekaterina Makarova 6-1, 6-1 in the second round.

Sania had earlier failed to make the cut into the main draw of the singles event after losing 3-6, 3-6 to Aravane Rezai of France in the first round qualifiers.

The 22-year-old Hyderabadi is the lone Indian surviving in the tournament after Mahesh Bhupathi and his Bahamian partner Mark Knowles bowed out in the second round of the men's doubles event yesterday, losing to Stephen Huss of Australia and England's Ross Hutchins 4-6, 5-7.

Meanwhile, Leander Paes and his Czech partner Lukas Dlouhy, seeded third, pulled out due to Dlouhy's illness after getting a bye in the first round.