Mack Horton said he would have carried out his anti-doping podium protest against China's Sun Yang even if he had known fellow Australian swimmer Shayna Jack failed a drugs test.
The Olympic 400 metres gold medallist snubbed Sun for a photo-call and refused to shake his hand after a medal ceremony at last month's world championships in South Korea, following a drug-testing controversy involving the Chinese star.
His stance won support among fellow competitors but provoked a furious reaction in China, which only intensified when it emerged Jack failed an out-of-competition test in the lead-up to the world titles.
She returned home before the meet started and Horton only learned of her positive result -- which she has vowed to fight -- after his protest. But he insisted it would not have affected his decision to take a stand.
"It was hard. It's really hard," he told Channel Seven late on Sunday, describing his reaction on hearing about Jack's positive test. But Horton added that "nothing changes" about his podium protest.
"The difference being, as soon as she returns a positive sample, she's returned to Australia, she's not competing at a world championships," he said.
"That gives me faith in the Australian system. We won't let our own athletes get away with it, (so) we can question and demand more from the rest of the world."
- 'I wavered. I wasn't sure' -
Sun, who served a three-month drugs ban in 2014, was vilified in South Korea following a leaked FINA doping panel report that alleged he allowed blood vials to be smashed with a hammer after being visited by testers last year. He denies any wrongdoing.
The governing body cleared him to compete at the championships after the testing incident, but the World Anti-Doping Agency has appealed the decision to the Court of Arbitration for Sport.
Horton began his war of words with Sun at the 2016 Rio Olympics when he labelled him a "drug cheat", but he insisted his protest was more about "how the way the sport is governed and controlled".
"Athletes are frustrated with doping in sport, they're frustrated with the system letting them down, and that athletes who are under investigation should not be competing at a world championships," he said.
Horton revealed he had been thinking about his protest in the days ahead of the 400m final, where he finished second behind Sun. But it was a last-minute decision to go ahead.
"I wavered. I wasn't sure. I was tense. It was awkward, no one really knew what to do and then all of a sudden the crowd realised what was going on and started, I guess, applauding," he said.
"That filled me with emotion and I was like, 'OK, this was the right thing to do.'
"Later I walked into the dining hall and the US team started applauding and then the rest of the dining hall starting applauding me as I walked in. And that was overwhelming as well."
Australia's Mack Horton refused to join China's Sun Yang for a photo call on the podium after the world 400m freestyle final.