STUTTGART, Germany (Reuters) - World number three Garbine Muguruza was forced to retire with a back injury during her round of 16 match against Anastasia Pavlyuchenkova at the Stuttgart Open on Thursday.
Russian Pavlyuchenkova won the first set 7-5 before Spaniard Muguruza, the second seed, called it quits.
Caroline Garcia beat Ukrainian qualifier Marta Kostyuk 6-1 3-6 7-5 to book her place in the quarter-finals.
World number seven Garcia, who overcame Maria Sharapova in the first round, faced another stern test before taming the 15-year-old Kostyuk in one hour and 41 minutes.
“She plays great, moves well, and fights a lot on court. For me, it was a difficult match to prepare for, because I didn’t know what to expect,” Garcia said.
Kostyuk had advanced to the main draw by beating France’s Alize Cornet and dumped out Antonia Lottner in the first round.
“There aren’t many videos or stats on her because she’s brand new on tour, so that’s never easy. She just went for it,” Garcia said.
Up next for Garcia is another Ukrainian in Elina Svitolina. The third seed was leading 2-6 6-1 3-2 when her opponent Marketa Vondrousova retired due to a thigh injury.
Former world number one Angelique Kerber was down a set and trailed by two games in the second against Estonia’s Anett Kontaveit when she pulled out with a quad problem.
America’s CoCo Vandeweghe battled past Laura Siegemund 6-4 4-6 6-3 to set up a last-eight showdown with top seed Simona Halep while Karolina Pliskova beat Veronika Kudermetova and next meets former French Open champion Jelena Ostapenko.
Reporting by Shrivathsa Sridhar in Bengaluru, editing by Ed Osmond