Rising sprint star Lachie Kennedy openly welcomes his rivalry with fellow young gun Gout Gout — but has cast doubt over a potential Australian Athletics Championships showdown between the pair in Sunday’s 200m final.

After Gout’s pair of 9.99 second runs in the under-20 100m went down as unofficial times due to illegal tailwinds, Kennedy landed an impressive blow in the blossoming rivalry at WA Athletics Stadium.

Kennedy ran a startling 10.0 seconds in the open 100m on Friday evening, the second-quickest legal time ever by an Australian over 100m behind Patrick Johnson’s 2003 national record of 9.93.

The 21 year-old run came hot on the heels of Gout’s heroics on Thursday and just a few weeks after the duo’s titanic tussle in the 200m at the Maurie Plant Meet in Melbourne which Kennedy won.

Kennedy admitted he watched with more than a hint of envy Gout has broken the 10-second mark — albeit unofficially — before him.

“Me and Gout are close, I was buzzing for him. I’m upset he beat me to it, but I’m gonna try and do it legal,” he said.

“The race for a legal 19 (second 200m) and the race for a legal nine (second 100m), it’s so on.

“There’ll be a bit of chirping for sure, but it’s all good fun.”

However, while Kennedy confirmed he would line up for the 200m heats on Sunday, he said his health would remain a priority and could not guarantee whether he would also race the final.

“Sunday’s going to be incredible, if the body’s up for it, of course,” he said.

“But I’m definitely going to be gunning for that 200 as well.

“It really just depends on how the body’s feeling. I plan to do the final, but if I’m feeling tight, I’m not going to risk the rest of my season just to get a 200m national champ medal.”

Before the 200m final, Kennedy will have a 100m semi and likely a final to navigate and while he will be a red-hot favourite, it will not be a walk in the park.

Rohan Browning, the man previously the second-quickest Australian over 100m (10.01) has an unofficial, wind-assisted sub-10 run to his name having run a windy 9.96 in 2021.

Browning, who was second-quickest in Perth on Friday night with a 10.07 which was scrubbed off due to a +2.1 tailwind, joked he could not get Gout off his social media feed after Thursday night.

But he welcomed the challenge Kennedy presented in the 100m.

“He’s in great shape, had a great season. That’s what you want for the sport,” he said.

“The depth coming through is really strong. To be honest, it’s even inspiring to me as someone who’s older than these guys.

“It bodes really well for the relay. It’s good for the health of the sport. I’m hoping I can delay the changing of the guard a bit longer, but those guys are right there.”