When Susie O'Neill had the biggest 'failure' of her career, thousands were cheering.

When Susie O’Neill touched the wall in the 200m butterfly final at the 2000 Sydney Olympic Games, the 18,000-strong crowd was already on its feet. As fellow Australian, Petria Thomas, followed milliseconds later, the stands erupted.

Two of our greatest swimmers had clinched medals on home turf.

But in that moment, Susie O’Neill was numb. Confused. Unsure what to do next. Because the medal she was soon to have placed around her neck wasn’t the colour she wanted or expected for the final race of her Olympic career.

American Misty Hyman had finished first, ending the Aussie’s six-year winning streak. No one saw it coming; least of all O’Neill, who had qualified for the final by breaking swimming’s longest-standing world record — a 19-year-old time of 2:05.81. She was far and away the favourite. She was ‘Madame Butterfly’.

On Monday, O’Neill watched the footage of that event for the first time while live on air for her Brisbane morning radio show, Ash, Kip, Luttsy & Susie.

And she cried.

Watch Susie’s reaction to her career-ending race below. Post continues after video.

Searching for breath between sobs, the now 46-year-old said she still grapples with the events of that day.

“I know it’s only a swimming race and I know in my head I didn’t fail, but with that I just see failure,” she said. “I felt like this was my race — home crowd. And to come second, for me, is failure.”

She recalled telling herself to be a good sport, to congratulate her competitor when the race finished. But inside she was hurting.

“I was thinking, ‘Why is everyone cheering?'” she said. “‘We’re in Australia.'”

The support of the crowd, the gold medal she'd won in the 200m freestyle the previous night, none of it mattered in that moment. And even now she struggles to see past what went wrong.

"I was really nervous for the whole Olympics. I’m a nervous competitor but that was the worst I’ve ever felt,” she said.

“Maybe I was too arrogant, maybe I’d lost too much energy from not sleeping night after night...

“Of course I thought I was going to win. I’m still trying to find reasons even 19 years later.”

Cathy Freeman: "I was immediately disappointed".

O'Neill's reaction isn't greed or arrogance. It's the psychology of an athlete, a person who's spent their entire life fixated on achieving a single goal.

At the same Olympics that O'Neill experienced her self-described 'failure', another Australian sporting legend, Cathy Freeman, achieved what appeared to be the ultimate success — a gold medal in her pet event, the 400m.

But speaking to The Howie Games podcast in 2017, the running champion said that all she felt in the moments after she crossed the line was 'disappointment'.

"I know I could have run faster than what I actually have, but that’s fine,” Freeman said.

“I actually crossed the line, looked across at the time — 49.11 — I was immediately disappointed because I would have loved to have run 48.

“I just remember leaning over, putting my hands around my knees and just shaking my head... I was not happy.

“It’s a mighty occasion. I don’t mean to sound like a Debbie Downer, but that’s just who I am.”

Cate Campbell: "Australia's poster girl for failure".

Six years later, Cate Campbell became 'Australia's poster girl for failure'. Those are her words, the words of a World Champion. It was a phrase Campbell used in a viral open letter addressing her surprising sixth-place finish in the 100m freestyle 2016 Rio Olympics. A performance she'd described at the time as the "greatest choke in Olympic history".

"You could not have been more ashamed of me than I was of myself," she wrote in the 2018 letter.

"You could not have judged me harsher than I was (and to an extent still am) judging myself.

"For future reference, when you see someone choking, it's not because they don't care — it's because they care too much."

She didn't care about winning for the sake of the glory; she cared for the sake of everyone who had invested time in helping her achieve a specific end.

"I had under 60 seconds to fulfil, not only my dream, but the dreams of a nation, a swim team, a coach, a family," she wrote.

But reflecting on what happened, Campbell said she's learned an important lesson about failure.

"It’s seen as a dirty word, something that we should be ashamed of," she wrote. "But let me tell you, it takes a hell of a lot of time, effort, diligence, perseverance and above all courage to get to a place where failure is possible."