Golfer Rory McIlroy has withdrawn from the 2016 Olympics saying that the Zika virus is "a risk" he is "unwilling to take".
The Zika virus has spread to South America where the Rio de Janeiro Olympics will be held in Brazil this summer.
Zika is spread by mosquitos and there is evidence that it linked to birth defects – in particular, abnormally small heads (microcephaly) - and possible neurological problems in adults. However, the International Olympic Committee, with guidance from the World Health Organisation, has resisted calls for the Games to be moved or postponed.
The situation is a blow for the sport with golf returning to the Olympics for the first time since 1904.
In an interview with the BBC last month the 27-year-old Northern Irishman had said that if he believed the virus threat posed a threat to his and fiancee Erica Stoll's plans to become parents in the future, he would not travel to Brazil.
The world number four is one of a number of high-profile golfers to pull out with Adam Scott, Louis Oosthuizen, Charl Schwartzel, Marc Leishman and Vijay Singh having already said they will not travel to Brazil.