Sprint star Lachie Kennedy says he's battling soreness and is no certainty to take part in the blockbuster 200m showdown with Gout Gout at the Australian Athletics Championships in Perth.

Kennedy cut a despondent figure after finishing second to Rohan Browning in the 100m final and could miss Sunday's eagerly awaited duel.

In a thrilling photo finish, Browning posted 10.01 (.001) to pip Kennedy's 10.01 (.006) in a race for the ages.

Kennedy entered the meet confident he could become just the second Australian to crack the magical 10-second barrier.

He had to be content with second place in the final, and a time of 10.00 in his heat on Friday.

Sadly for athletics fans, Kennedy has cast doubt on his participation in Sunday's half-lap showdown with 17-year-old Gout.

The 200m heats are scheduled for 12.45pm WST, with the final at 3pm WST.

"I'm definitely sore, definitely a little tight, but we'll see how we pull up tomorrow," Kennedy said on Saturday night.

"At this stage, I still want to do the (200m), but it's all about how the body feels after a night's sleep."It will sort of be like a vibe thing, like how the body feels, how the legs feel. If they're feeling tight just walking around, I'll probably call it

"I've got nothing to prove. It'll just be like, how I feel sort of thing."

Gout broke Peter Norman's 56-year-old Australian 200m record late last year when he clocked 20.04 seconds - a time faster than spring king Usain Bolt ran at the same age (20.13).

But Kennedy caused an upset last month when he posted 20.26 to beat the teenager by four-tenths of a second at the Maurie Plant Meet in Melbourne.

Kennedy eased up slightly in running his 10.00 during his 100m heat on Friday.

In hindsight, that cost him the chance to crack 10 seconds then and there, but he's confident it's just a matter of time before he achieves the feat.

"I'm sad I didn't crack 10," Kennedy said.

"But there'll be plenty of opportunities to crack 10 down the line, so I'm not too stressed about it."

On a busy final day of the Championships, Kurtis Marschall will be aiming to crack the 6m barrier for the first time when he competes in the men's pole vault final.

Three-time Olympian Peter Bol will do battle with Peyton Craig and Luke Boyes in the 800m final, while Olympic medallists Nicola Olyslagers and Eleanor Patterson headline the women's high jump.