Troon - Camilo Villegas of Colombia pulled out of the Olympics on Monday because he is trying to keep his job on the PGA Tour.
Villegas had indicated for the last two weeks that he wanted to be in Rio for golf's return to the Olympics for the first time since 1904.
While he considered the Zika virus - Villegas and his wife are trying to start a family - his main concern was work.
Having pulled out the Barbasol Championship last week with a thumb injury, he is No 146 in the FedEx Cup standings.
Only the top 125 advance to the playoffs and keep full cards for the following season, and Villegas has only four tournaments left. He is playing the RBC Canadian Open this week.
"This is an incredibly difficult decision for me, but ultimately I have to do what's best for my career," Villegas said.
He is the 21st male golfer to withdraw from the Olympics, and he joins Brendon de Jonge of Zimbabwe in citing his job security for pulling out.
"Right now, I have not secured my PGA Tour card for next season and I have several opportunities to improve my FedEx Cup standing, one of which overlaps with the Olympics," he said.
"I have waited until the last minute to withdraw as I have been working hard to secure my playing privileges so I can continue to represent Colombia on the PGA Tour."
By withdrawing, Colombia will not have a male golfer in the Olympics next month.
Villegas would be replaced by Jose-Felipe Lima of Portugal, which now will have two players in the 60-man field.
The 21 players who have pulled out include the top four in the world - Jason Day, Dustin Johnson, Jordan Spieth and Rory McIlroy.
The Olympics at least will have two of the major champions from this year in Masters winner Danny Willett of England and British Open champion Henrik Stenson of Sweden.