Stuttgart Open: Garbine Muguruza among three retirements in last 16

Image source, Getty Images

Image caption, Garbine Muguruza has retired through injury seven times since the start of 2017

Wimbledon champion Garbine Muguruza was one of three players forced to retire in the last 16 of the Stuttgart Open.

The Spanish second seed pulled out with a back problem after losing the first set 7-5 against Russian Anastasia Pavlyuchenkova.

Germany's Angelique Kerber withdrew with a leg injury after going 6-0 2-0 down against Estonia's Anett Kontaveit.

Czech Marketa Vondrousova won the first set against Ukraine's Elina Svitolina but also quit with a leg problem.

Third seed Svitolina, who recovered to lead 2-6 6-1 3-2 before Vondrousova's retirement, will now play French sixth seed Caroline Garcia, who overcame Marta Kostyuk of Ukraine 6-1 3-6 7-5.

Kontaveit and Pavlyuchenkova now face each other in the quarter-finals, while American Coco Vandeweghe booked a meeting with top seed Simona Halep after winning 6-4 4-6 6-3 against defending champion Laura Siegemund of Germany.

Czech fifth seed Karolina Pliskova beat Russia's Veronika Kudermetova 7-6 (7-4) 6-3 and will now meet fourth seed Jelena Ostapenko after the Latvian won 6-3 6-0 against Zarina Diyas of Kazakhstan.