Fellow Australian Aidan Murphy also cracked the 20-second mark, coming second in 19.88 -- the two quickest times of the year and with a legal tailwind.

"This is what I've been waiting for," said Gout at the Sydney Olympic Park Athletic Centre.

"We have such incredible athletes in Australia and me being able to race these athletes, we push each other to the limits. Two Australians sub-20. I mean, this is amazing."

The 18-year-old burst on the scene in 2024 when he clocked 20.04 seconds at the Australian All Schools Athletics Championships.

It shattered Peter Norman's national record of 20.06 from the 1968 Olympics and was the quickest ever by a 16-year-old.

He had improved to 20.02 but never gone under 20 seconds legally before.

His time was faster at the same age than Bolt, who ran 19.93 in 2004.

"There's a big weight off my shoulders knowing I ran it legally, and I have the speed and my body to run times like that. So, it definitely feels great, and ready for more," Gout said.

The race was billed as a showdown with his closest Australian rival Lachlan Kennedy.

But 22-year-old Kennedy, who is also on a rapid rise, withdrew after executing flawlessly to win the 100m in 9.96 on Saturday -- the fastest time run by an Australian on home soil.

He also clocked 9.96 in his heat.

"It's the standard I've set now, so hopefully I can go a bit quicker next time and see where it takes me," Kennedy said. "I think the sky is the limit."

- Hull treble bid fails -

World under-20 mile record holder Cameron Myers reinforced his potential by running 3:29.85 in the 1500m, edging out reigning Commonwealth Games champion Oliver Hoare.

It was the best time globally this year and the quickest ever in Australia.

The 19-year-old Myers backed up by taking out the 5000m in a personal best 13:11.66.

But Paris Olympic 1500m silver medallist Jessica Hull's bid for a rare 800m-1500m-5000m treble fell apart.

Hull was leading the 1500m with 100m to go, but was clipped from behind and dramatically fell with fellow Olympian Claudia Hollingsworth crossing first.

Hollingsworth was initially disqualified over the incident, but reinstated on appeal.

Hull pulled out of the 800m, won by Abbey Caldwell in 1:58.57, but returned to win the 5000m in 15:13.21.

The four-day meet also saw Olympic pole vault champion Nina Kennedy clear 4.65m to stand on top of the national podium for the fifth time in her career.

Kennedy continues to jump off a restricted run-up as she returns from a long injury layoff ahead of defending her title at the Glasgow Commonwealth Games in July.

"I'm happy with how I jumped. I got the win pretty comfortably out there, so there is no need to push the body," she said.

High jump world champion and Olympic silver medallist Nicola Olyslagers cleared 1.99m to outleap Olympic bronze medallist Eleanor Patterson (1.93m).