Ryder Cup team-mates Rickie Fowler and Patrick Reed will compete for the USA at the Olympics in Rio next month.
US Open champion Dustin Johnson opted out because of concerns over the Zika virus, which has been linked to defects in newborn babies.
World number seven Fowler, 27, said he was "looking forward to wearing some red, white and blue in Rio".
Reed will deputise for Johnson, while world number three Jordan Spieth is set to make a decision on Monday.
Spieth, 22, said in June he expected to compete in Rio.
World number two Johnson's withdrawal means three of the world's top four players will be absent - Jason Day and Rory McIlroy have also pulled out - when golf returns to the Olympics after a 112-year absence.
Adam Scott and Louis Oosthuizen are among the other major winners who will not take part.
World number 13 Reed had expressed concerns over Zika but, after finishing joint 10th at the Scottish Open on Sunday, he said: "I got the email and phone call from Team USA.
"I went through a lot of things with them and we're all in. We can't wait to go and play for USA and have some fun."
Asked what information he had received, the 25-year-old said: "Basically how everyone is, how the Zika virus is doing and security. Those were my only concerns.
"Yes, it's a risk, but I feel like it's a risk that we are all willing to take."
The Olympics take place from 5 to 21 August, with the men's golf tournament from 11 to 14 August.
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