Porsche Tennis Grand Prix

Stuttgart Open: Angelique Kerber, Garbine Muguruza out due to injuries; Jelena Ostapenko reaches quarter-finals

Angelique Kerber had to quit with a right thigh injury at the Stuttgart Open and was swiftly followed by Garbine Muguruza, who called it quits with back pain.

Stuttgart Open: Simona Halep survives scare to reach third round; Anastasia Pavlyuchenkova upsets Madison Keys

Top seed Simona Halep, a semi-finalist last year at the Stuttgart Open, battled to a 4-6, 6-2, 6-3 second round win over Magdalena Rybarikova.

Angelique Kerber defends Stuttgart title, drives home with another Porsche

Sania-Hingis lose their first competitive match as a doubles team

Before Wednesday's defeat, Sania and Martina won back-to-back-to-back titles at Indian Wells, Miami and Charleston, a run which helped the India become the world's No.1 women's doubles player.