Soon after, she thought of her father, who died of brain cancer last year after fighting for years to see his girl swim at an Olympics.

The Queenslander collects Australia’s third gold of the Tokyo Games.

And her 100-metre backstroke triumph is the most emotional, won against a backdrop of family tragedy.

McKeown’s dad, Sholto, died in August last year.

Had Tokyo’s Games not been postponed a year because of the coronavirus pandemic, he would have watched Kaylee swim at an Olympics.

Sholto’s death has given McKeown perspective beyond her 20 years.

“It’s not necessarily what I’ve been through,” McKeown said.

“Everyone has had a journey of their own.

“It’s having that really tough mindset and I wouldn’t have had it any other way.

“I don’t think I’d be here today with all that’s happened.”

McKeown entered Tuesday’s final as world record holder but third-fastest qualifier behind American Regan Smith and Canada’s Kylie Masse.

The Canadian and American led at the last turn only for McKeown to surge in the last 25 metres for a stunning victory.

“My legs we’re definitely hurting a lot with 20 (metres) to go,” she said.

“But I trained for that and knew I had a really good chance to be on the podium and come away with the position I have.”

McKeown triumphed in 57.47 seconds, with Masse (57.72) taking silver and Smith (58.05) the bronze.

Australian veteran Emily Seebohm, at her fourth Olympics, finished fifth in 58.45.

“To see Kaylee there, I want to say, it was effin’ special,” Seebohm said.

Also Tuesday, Mitch Larkin finished seventh in the 100m backstroke final while 400m freestyle gold medallist Ariarne Titmus booked another date with American Katie Ledecky.

After their epic 400m battle, the pair won separate 200m freestyle semi-finals.

Titmus was restrained for three laps and then powered to win in one minute 54.82 seconds.

“I felt a little bit sluggish which was understandable,” Titmus said.

“It was just about trying to execute a good race.”

Reigning Olympic champion Ledecky then clocked 1:55.34.

The next chapter in the Titmus versus Ledecky story comes in Wednesday’s final.

But the Australian warned against writing off the rest of a field including compatriot Madi Wilson, who snuck into the final in lane eight.

“I enjoy racing Katie, it’s exciting for everyone and myself,” Titmus said.

“But the 200 tomorrow is not just Katie and I. It’s a very strong field … it’s anyone’s race.”