Less than two weeks before the start of her title defense, Wimbledon champion Marketa Vondrousova suffered a shock injury.
The Czech slipped and fell while leading 5-3 in the first set of her second-round match against Anna Kalinskaya at the Berlin Open.
Vondrousova held her right hip and took a medical timeout before retiring two games later at 5-5.
Wimbledon will take place from July 1 to 14. Vondrousova will begin defending her title on the second day.
The 24-year-old became the first unseeded player to win the Wimbledon women’s singles title when she defeated Ons Jabeur in the final.
The Russian Kalinskaya will face either world number three Aryna Sabalenka or her compatriot Daria Kasatkina in the quarterfinals.
Elsewhere on Thursday, third seed Elena Rybakina reached the quarterfinals with a 6-4, 7-5 win over Veronika Kudermetova.
Kazakhstani Rybakina, the 2022 Wimbledon champion, will next play against former world number one Victoria Azarenka.
Eight of the world’s top 10 players will compete in Berlin, with only top seed Iga Swiatek and world number seven Jasmine Paolini missing.