Australia's Olympic icon, Ian Thorpe, is set to become the face of a national campaign in support of same-sex marriage.
The equality campaign is calling on Australians to vote in support of same-sex marriage after the Federal Government's decision to conduct a postal poll.
The voluntary postal vote on the issue will be held in September after the Turnbull Government's preferred compulsory plebiscite was blocked for a second time by the Senate
Thorpe, Australia's most successful Olympian, first opened up about his sexuality in 2014 and has spoken about his journey coming out to family and friends.
"The reason why it's personally important for me is the message it sends to a young me -- that the way that I felt is equal to the way anyone else feels," Thorpe said on Sunday.
Thorpe, the winner of five OIympic gold medals, spent Sunday morning in Sydney getting out the 'Yes' vote before the City2Surf fun run.
Thorpe's support will be a big boost for the national 'Yes' campaign for marriage equality, which is calling on all Australians to register to vote and update their electoral details for a postal plebiscite.
Before the postal vote goes ahead, the High Court will hear two legal challenges to the plan just days before ballots are due to be mailed out to voters.