Azarenka pulls out of Madrid Open with back injury

Tennis - Madrid Open - Victoria Azarenka of Belarus v Alize Cornet of France - Madrid, Spain - 2/5/16 Azarenka returns the ball. REUTERS/Susana Vera

(Reuters) - Fourth seed Victoria Azarenka pulled out of the Madrid Open with a back injury on Wednesday ahead of her third round game against American Louisa Chirico.

The 26-year-old Belarusian had been the highest seed left in the women's draw after Agnieszka Radwanska, Angelique Kerber and Garbine Muguruza all lost.