Unfancied Adam Spencer and established international star Jessica Hull have taken down high-quality fields to win the 1500m titles at the Australian track and field championships in Adelaide.
Tokyo Olympics finalist Stewart McSweyn did much of the front-running in the men's race on Saturday and Commonwealth champion Olli Hoare and teen sensation Cameron Myers were both in contention throughout.
But it was Spencer who had the best kick in the final straight as he powered home to win in three minutes 37.68 seconds ahead of Hoare and Jesse Hunt.
"I didn't expect it," said the 22-year-old Spencer, who made a massive improvement in 2023, lopping five seconds off his personal best.
"I thought I was going to fall over in the last 20 metres.
"My legs were hitting lactic and I saw the shadows of everyone coming up but I managed to get over the line so I'm pretty happy."
Spencer could be named in the Paris Olympics team on Sunday or the selectors could leave all three spots in the men's 1500m vacant for now, giving the other contenders more time to press their cases.
The situation is more clear-cut in the women's 1500m, given the dominant nature of Hull's victory and her international pedigree.
She made the decisive move at the bell, surging away from national record holder Linden Hall and Georgia Griffith to win in a fast time of 4:01.39.
"That's so special," said Hull of the prospect of going to a second Olympic Games.
"Part of me doesn't really think about that because I had to get the job done today.
"But a second Olympics - I could never have believed it."
Hull was hopeful of being named in the Olympic team at the conclusion of the national titles.
"I tick all the boxes," said the consistent 27-year-old, who was 11th in the Tokyo Olympics 1500m final, seventh at each of the past two world championships and fourth at the world indoors earlier this year.
"You never know, but I've got my fingers crossed I'm going to be there."
Eighteen-year-old Sebastian Sultana caused a boilover to win the men's 100m in 10.27 seconds.
Josh Azzopardi was second in 10.39 and pre-event favourite Rohan Browning was fourth in 10.41 after battling a knee niggle.
"It feels amazing," said Sultana.
"After the semi I knew I could get it done, but to actually get it done was really good.
"Obviously (Browning) is a great athlete but I try to just focus on myself really, work on my execution."
Sultana's next target is the World Relays in the Bahamas in May, where Australia's is looking to secure Olympic qualification in the men's and women's 4x100m events.
There was also a surprise winner in the women's 100m, with Naa Anang claiming a second national title in 11.34, five years after her first.
The minor medals went to Ella Connolly (11.37) and Ebony Lane (11.41) in the absence of national record holder Torrie Lewis, who has chosen to focus on the 200m this weekend.
The performance of the day came from Matthew Denny who smashed his own national discus record with a huge heave of 69.35m.
Having finished fourth at the Tokyo Olympics and 2023 world championships, the big Queenslander is now a legitimate gold-medal contender in Paris.
World championships bronze medallist Mackenzie Little won the women's javelin with 61.85m ahead of veteran Kathryn Mitchell (60.28m) and two-time world champ Kelsey-Lee Barber (55.13m).
