The International Golf Federation (IGF) has confirmed Jordan Spieth will not participate at the Olympic Games next month.
The 22-year-old has followed Jason Day, Rory McIlroy and Dustin Johnson in pulling out, meaning none of the world's top four male players will be present as golf returns to the Olympics for the first time since 1904.
Spieth's absence, announced by IGF president Peter Dawson on Monday at a media conference ahead of The Open at Royal Troon, means Matt Kuchar will now represent the United States in Rio, along with Patrick Reed, Rickie Fowler and Bubba Watson.
In addition to the world's top four, several other high-profile players, including Australian Adam Scott and South African Charl Schwartzel, have opted not to compete in Brazil due to fears over the mosquito-borne Zika virus, which has been linked with birth defects.
Spieth is due to address the media at Troon on Tuesday, when he is expected to confirm health concerns are behind his decisions.