Dutch fourth seed Kiki Bertens, one of the favourites for the French Open, retired from her second round match through illness on Wednesday.
The 27-year-old, a semi-finalist in 2016, was trailing Slovakia's Viktoria Kuzmova 3-1, 40-15 when she called for the doctor, complaining she was suffering from "shaking and no energy".
Bertens was seen as a potential champion in Paris having won the Madrid title without dropping a set, the first woman to achieve the feat.
Kuzmova goes on to face either Britain's Johanna Konta or Lauren Davis of the United States for a place in the last 16.
World No 46 Kuzmova had already defeated Bertens in Dubai this year before the Dutchwoman gained revenge in Miami.
She has now made the last 32 of a grand slam tournament for the first time.
