Bryson DeChambeau described himself as "desperately disappointed" after a positive test for COVID-19 ruled him out of competing in the golf competition at Tokyo 2020.
A statement from the PGA Tour confirmed the 2020 US Open champion failed the final testing protocol before heading out to the Japanese capital to represent Team USA.
In his place comes Patrick Reed, who is undergoing testing on Sunday and Monday before departing for Japan.
Should he clear that hurdle Reed will become a two-time Olympian having also competed at Rio 2016. He joins Justin Thomas, Open Championship winner Collin Morikawa and Xander Schauffele as part of a star-studded USA line-up in the men's event.
"I am deeply disappointed not to be able to compete in the Olympics for Team USA," said DeChambeau.
"Representing my country means the world to me and it is was a tremendous honour to make this team.
"I wish Team USA the best of luck next week in Tokyo. I will now focus on getting healthy, and I look forward to returning to competition once I am cleared to do so."
Bryson DeChambeau is unable to compete at the Olympics after testing positive for COVID-19.— PGA TOUR (@PGATOUR) July 25, 2021
Patrick Reed will take his place in Tokyo.
Reed added: "I am so excited to have the opportunity to represent our country and be a part of Team USA in Tokyo.
"I wish Bryson nothing but the best, and I know how disappointed he is to not be able to compete, and I will do my best to play my best and represent our country."