Rory McIlroy feels playing in this summer's Olympics is not worth the risk after announcing his withdrawal due to concerns over the Zika virus.
The Northern Irish world number four, who was due to represent Ireland in Rio in August, has become the latest high-profile golfer to say he will not travel to Brazil.
He follows Charl Schwartzel, Marc Leishman and Vijay Singh in pulling out over the Zika issue, which has cast a shadow over the build-up to the Games.
Four-time major winner McIlroy, 27, said in a statement: "After much thought and deliberation, I have decided to withdraw my name from consideration for this summer's Olympic Games in Rio de Janeiro.
"After speaking with those closest to me, I've come to realise that my health and my family's health comes before anything else.
"Even though the risk of infection from the Zika virus is considered low, it is a risk nonetheless and a risk I am unwilling to take.
"I trust the Irish people will understand my decision. The unwavering support I receive every time I compete in a golf tournament at home or abroad means the world to me."
Ireland's team leader Paul McGinley, the former Europe Ryder Cup captain, said: "As much as I'm disappointed like all Irish people are, you have to respect his decision not to play.
"I think it is a great opportunity for golf to come back into the Olympics and showcase the game around the world but ultimately each individual has to have their own view, and it is not up to me to get involved when it comes to something like health concerns."
Zika is carried by mosquitoes and has been linked to defects in babies.
The World Health Organisation declared the Zika epidemic to be a global emergency in February but its latest advice is that the risk of international spread as a result of the Olympics is "very low".
The International Olympic Committee, acting on WHO advice and with Brazilian authorities, is confident the situation is safe. The Games also take place during the South American winter, when there should be fewer mosquitoes.
Despite that, pregnant women have been advised not to travel to Brazil.
Britain's 2012 long jump gold medallist Greg Rutherford has had sperm frozen over Zika fears and American cyclist Tejay van Garderen, whose wife is pregnant, has also pulled out.
Concern among golfers has been high with world number six Rickie Fowler also casting doubt over his participation recently.
With two other major winners in Louis Oosthuizen and Adam Scott having withdrawn for family and scheduling reasons, it is a blow for golf as it returns to the Games for the first time since 1904.
A statement from the International Golf Federation, the sport's Olympic governing body, read: "The IGF is disappointed with Rory's decision but recognises that some players will have to weigh personally a unique set of circumstances as they contemplate their participation in golf's historic return to the Olympic Games in Rio de Janeiro, with the Zika virus foremost among them.
"It is unfortunate that the Zika virus has led to Rory's decision to withdraw from the Olympic Games, knowing how much he was looking forward to taking part.
"As we have stated before, the Olympics is the world's greatest celebration of sport and we remain excited about golf's return after a 112-year absence. It will truly be a special occasion for our sport and we are confident that the 60 men and 60 women who will represent their respective countries will find it an experience they will cherish forever."
McIlroy had pledged his allegiance to Ireland having also been eligible for Great Britain.
A statement from the Olympic Council of Ireland read: "The OCI is extremely disappointed not to be taking Rory with us to Rio.
"However, as we have always said, it is down to the individual and of course we respect his decision, which he has taken for personal reasons.
"Rory was set to be one of the big stars of Rio 2016, but now there is an opportunity for another Irish golfer to take up the chance to become an Olympian."
The situation concerning Zika in Brazil will continue to be monitored by the IOC but Dr David Heymann, chairman of the WHO's emergency committee on the virus, said last week: "The committee concluded that there is a very low risk of further international spread of Zika virus as a result of the Olympics and Paralympics, which is already low."