After the only second-round match held on Wednesday, in which Simona Halep progressed past Magdalena Rybarikova, the rest of second-round action completed on Thursday, defining the quarterfinal draw of the Porsche Tennis Grand Prix in Stuttgart.
The day was marked by three retirements: second seed Garbine Muguruza withdrew with a back problem after losing the first set of her encounter with Anastasia Pavlyuchenkova, Angelique Kerber pulled out with a leg injury after dropping eight straight games to Anett Kontaveit, and Marketa Vondrousova had to quit her match with Elina Svitolina midway through the third set because of a leg problem.