Golfers Bryson DeChambeau and Jon Rahm are out of the Tokyo 2020 Olympics after testing positive for Covid-19.
American DeChambeau had not yet travelled to Japan, where he was set to make his Olympic debut.
Spain's world number one Rahm has tested positive for the second time in as many months.
He had to withdraw from the USPGA Memorial Tournament in Ohio in June after returning a positive sample, before going on to win the US Open.
Both Rahm and DeChambeau played at The Open at Royal St George's in Kent last week.
"I am deeply disappointed not to be able to compete in the Olympics for Team USA," said world number six DeChambeau, who has been replaced in the US team by Patrick Reed.
"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."
Reed, who will now become a two-time Olympian, said: "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."
The Olympic golf competition starts on Thursday.
Meanwhile the Spanish Olympic Committee has informed the International Golf Federation that Jorge Campillo will replace Jon Rahm as a representative of Team Spain in the Olympic Games Tokyo 2020.
Campillo will join Adri Arnaus in representing Team Spain for the men's competition which begins Thursday, July 29 at Kasumigaseki Country Club.