Caster Semenya is switching to the 200 metres ahead of the 2020 Tokyo Olympics following a rule change that could have affected her 800m title defence.
The 29-year-old won 800m gold at the 2012 and 2016 Games but athletics' world governing body, the IAAF, has introduced rules that mean Semenya and other athletes with differences of sexual development must either take testosterone-reducing medication to compete at track events from 400m to the mile, or switch to another distance.
Semenya disputed the implementation of those rules but lost a challenge in the Court of Arbitration for Sport and then in an appeal to the Federal Supreme Court of Switzerland.
Now, four months out from the Olympics, Semenya has revealed she will bid to make it to the Games in Japan as a 200m athlete.
"Ever since I saw the 2008 Beijing Olympic Games on television, I have known that I want to compete on the Olympic stage," the South African said in an Instagram post.
"My first international 800m medal came as a junior at the 2008 Commonwealth Youth Games in India, and over the next 11 years I have won gold at every major international competition including the Olympic Games, World Championships, Commonwealth Games, Diamond League and African Championships.
"However, as you are all aware, I am unable to compete in the 800m and defend my title at the Tokyo Olympic Games later this year.
"My dream has always been, and will continue to be, to compete at the highest level of sport, and so in order to pursue my goals and dreams, I have decided to change events, and compete in the 200m.
"This decision has not been an easy one, but as always, I look forward to the challenge, and will work hard, doing all I can to qualify for Tokyo and compete to the best of my ability for South Africa.
"Thank you to my team who have supported me over the past few months, and thank you to all South Africans who believe in me and stand behind me."
The qualifying time to reach the 200m in Tokyo is 22.80 seconds, with Semenya's current personal best over that distance 24.26s.