Former world number one Victoria Azarenka was forced out of the Aegon Classic in Birmingham with a foot injury on Wednesday shortly after defending champion Ana Ivanovic suffered a shock defeat.
Belarusian Azarenka won her first round match at the grasscourt event on Tuesday, beating American Varvara Lepchenko but was unable to take to the court for her second-round match against Kazakhstan's Zarina Diyas.
"It's very disappointing for me to make this decision but I tried to practice and it just doesn't feel 100 percent," the twice Australian Open champion who missed five months of the 2014 season with a foot problem, said in a statement.
"I don't think it's the best time for me to take a risk right now, especially right before Wimbledon and I need to make sure I have the best preparation possible."
Ivanovic double-faulted on match point down as she lost 6-4, 3-6, 7-6(6) to Portuguese qualifier Michelle Larcher De Brito.
Larcher De Brito is best known for knocking Maria Sharapova out in the second round of Wimbledon two years ago.
World number three and top seed Simona Halep of Romania defeated British wildcard Naomi Broady 6-4, 6-2.
Last year's Wimbledon runner-up Eugenie Bouchard's woeful recent run continued when the Canadian lost 6-3, 4-6, 6-0 to powerful French player Kristina Mladenovic.
