Bubba Watson is fifth in the world golf rankings and now the top rated player heading to the Rio Olympics.
His rise comes as defections persist with world no 3 Jordan Spieth the latest to emulate Jason Day, Dustin Johnson and Rory McIlroy with their Rexit decisions.
Spieth made his decision as he prepared for this week's British Open at Troon and was replaced in the US team by Matt Kuchar.
Others in the top 10 who have withdrawn are Adam Scott and Branden Grace as golf is readmitted to the Olympics for the first time since 1904. Only one woman, Lee An Paice, has withdrawn from the tournament.
Spieth cited the Zika virus for his absence as Games organisers reiterated that the World Health Organisation advised there should be no general restrictions on travel to Rio because of the mosquito-borne disease.
Golf is assured of a place in the 2020 Olympics in Tokyo but the IOC will vote next year to decide whether it will stay beyond that.