Seventeen-year-old Gout Gout won the Australian 200m title and broke the 20-second barrier with a wind-assisted performance in Perth.
He crossed the line in 19.84 seconds - 0.2secs faster than his own national record, but it was not official record because of a wind speed of +2.2 metres per second.
Gout became the second fastest under-20 200m sprinter in history in all conditions - behind American Erriyon Knighton, who clocked 19.49 at the LSU Invitational in 2022.
"Top speed is my gift. I used it, took off and I got sub-20, so I couldn't be happier," said Gout, who ran a legal 20.21 in the heats.
"I've been chasing getting that sub-10, focusing on my first 100, and that's exactly what I did. Feels pretty good."
Gout won the Under-20 100m title on Friday in 9.99, also with a tailwind above the permitted limit.