World number 16 Belinda Bencic has pulled out of next month's Olympic Games in Rio to focus on the US Open.The Swiss, 19, was forced to withdraw from the second round at this year's Wimbledon with a wrist injury.
"Although I have recovered from the wrist injury I am behind in my training schedule," she wrote on social media.
On Tuesday, Bencic's compatriot Roger Federer, the men's world number three, pulled out of Rio with a knee injury that has ended his 2016 season.
The US Open begins in New York on 29 August.
Also out of the Olympics - which start on August 5 - are Maria Sharapova, who is serving a doping suspension, fellow former world number one Victoria Azarenka, who is pregnant, world number five Simona Halep and Karolina Pliskova, who is ranked 17th.
In the men's tournament, Wimbledon runner-up and world number seven Milos Raonic and Tomas Berdych, ranked eighth, will also not compete.