Branden Grace, the highest-ranked South African golfer, withdrew from the Rio Olympics on Friday due to fears over the Zika virus.
Grace, No. 11 in the world, becomes at least the fourth golfer to cite Zika as the reason not to play in Rio de Janeiro, Brazil, this summer.
"After serious consideration, it is with regret that I have decided to withdraw myself from the Olympic competition due to the risk posed by the Zika virus," Grace, 28, said in a statement. "Although it was a huge goal of mine to represent my country in the Olympics, we are getting married in November and hoping to start a family in the near future, so I must put the health of my family first.
"It would have been a huge honor to represent my country, so I really hope to be able to qualify again in four years' time."
There is no vaccine for the Zika virus, which leads to severe birth defects. The mosquito-borne virus can cause babies to be born with abnormally small heads and adults to have possible neurological problems.
Rory McIlroy, No. 4 in the world and a four-time major winner, cited Zika in announcing Wednesday he would not represent Ireland in golf's return to the Olympics for the first time since 1904. McIlroy and his fiancee plan to start a family in the next few years.
Former Masters champion Charl Schwartzel of South Africa withdrew three weeks ago due to Zika. Schwartzel said he and his wife plan to have more children.
Marc Leishman of Australia also cited Zika because his wife's immune system has not fully recovered from nearly dying last year of toxic shock syndrome.
South Africa will be represented at the Olympics without its best three players -- Grace, No. 14 Oosthuizen and No. 23 Schwartzel.
The Rio Olympics are scheduled from Aug. 5-21.