Former Masters champion Charl Schwartzel is the latest high-profile player to opt out of the Rio Olympics.
The South African's decision comes a week after compatriot Louis Oosthuizen withdrew, while two other Masters champions, Fiji's Vijay Singh and Adam Scott of Australia, will also not play.
"We had a great team but now obviously it will not be as good," said South Africa team captain Gary Player.
Golf returns to the Olympics after a 112-year absence at the Rio games.
Three-time major winner Singh said fears over the Zika virus would prevent him competing in Brazil, while Scott pulled out in order to focus on the PGA Tour.
The Games take place from 5 to 21 August, with the men's golf tournament ending on 14 August.
Never want to miss the latest golf news? You can now add this sport and all the other sports and teams you follow to your personalised My Sport home.