US Open champion Jon Rahm became the second high-profile player on Sunday to be forced to withdraw after his own positive test for Covid-19.
Rahm had been required to take three PCR tests after his visit to the United Kingdom to compete in The Open and, while he produced negative samples for the first two, he had a positive result on the third.
"Jon Rahm tests positive for Covid-19 and will not play the 2020 Tokyo Olympics," said the Royal Spanish Golf Federation on its official website
Bryson DeChambeau has also been ruled out of competing at the Tokyo Olympics after testing positive for Covid-19/
Last year's US Open champion, sixth in the world rankings, was due to make his Olympic debut in Tokyo when the competition gets under way on Thursday.
Instead USA Golf announced that DeChambeau has been replaced by Patrick Reed, who joins Justin Thomas, Collin Morikawa and Xander Schauffele in the United States team as he heads to his second Games.
DeChambeau shot a final round of 65 at The Open last week to salvage a share of 33rd place after a tumultuous week, having hit out at his equipment providers after making 71 on the opening day.
"I am deeply disappointed not to be able to compete in the Olympics for Team USA," DeChambeau said.
"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 finished in a tie for 11th place in the Rio Olympics five years ago, said: "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."