Caleb Ewan's team hope he will be ready for the start of the Tour Down Under after illness forced the Australian sprint ace out of the warm-up event.
With the top sprinter in the field out of Saturday's twilight Down Under criterium, a six-rider breakaway unexpectedly stayed clear to decide the one-hour race.
With the bunch breathing down his neck, Equadorian Jhonatan Narvaez outsprinted his fellow escapees to take the win.
The main plan for Narvaez and his Ineos Grenadiers teammates had been to set up their sprinter Elia Viviani.
Instead, the Italian could be seen celebrating in the background as Narvaez scored his upset win.
"It's important to never lose the motivation to win the race," said Narvaez, who won a stage of the 2020 Giro d'Italia."
"To start the season like this is really nice ... I'm enjoying it a lot.
"That was the plan, to (set up) the sprint for Elia, but I was in the front and in the end it was easier to stay at the front than at the back."
The Adelaide CBD race was dominated by the shock news a few minutes before the start that Ewan had pulled out.
Top Australian team Jayco AlUla hope he will be ready for Tuesday's start of the six-day Tour Down Under, where he would be the top favourite for the sprint finishes.
Ewan, who won the Australian criterium championship again a week ago, was the No.1 rider in the criterium and a five-time winner.
Team doctor Matteo Beltemacchi said his decision to take Ewan out of Saturday's race was supported by team management.
"He's looking from his (hotel) window, 'c'mon Doc, I want to race, I want to race'," Beltemacchi told AAP.
"In the end, I won. My call was the winner.
"The good thing is he's not worsening and now, he's pretty normal.
"But this morning, he still had some light (symptoms) and I didn't want to take any risks for the Tour Down Under."
The standalone event is always raced a couple of days before Adelaide's Tour Down Under to give international riders a chance for some racing at the start of the season.
Ewan has rejoined Jayco AlUla, his first professional team, after a difficult end to his five-year tenure at Belgian squad Lotto Dstny.
He has endured a difficult couple of years since crashing out of the 2021 Tour de France with a broken collarbone.
Ewan and Jayco AlUla are hopeful his nationals criterium win signals a return to top form.
He arrived in Adelaide a couple of days before the Down Under criterium and became unwell after a training ride in Friday's blistering heat.
"As a precaution, we'd prefer for him not to start," Beltemacchi said.
"We did all the normal tests - he didn't test positive (to COVID-19)."
Saturday night's one-hour street race started as planned without the large-scale pro-Palestine protest that had been expected.
While there were Palestine flags in the crowd there were no disruptions at the start of the race.
The Israel Premier Tech WorldTour team features Australian riders Simon Clarke and Nick Schultz.
