Caleb Ewan took the sprint at the Tour Down Under Schwalbe Classic Criterium to make it four victories in five editions for the Australian.
The Lotto-Soudal sprinter beat out European road race champion Elia Viviani into second with his Cofidis team-mate Simone Consonni finishing third.
Jasper Philipsen (UAE Team Emirates) and Kristoffer Halvorsen (EF Pro Cycling) rounded out the top five with Britain's Chris Lawless (Ineos) making the top 10 in ninth place.
In his first outing wearing Deceuninck - Quick-Step colours, Sam Bennett found himself too far back to contest the sprint, with his lead-out man Michael Mørkøv instead finishing seventh.
Wet conditions blighted the peloton and a crash in the closing kilometres brought down a number of riders, splitting the peloton.
As EF Pro Cycling looked to set things up for Halvorsen, Ewan launched his sprint early from the right-hand side of the road. He quickly opened up a gap as Viviani and the others looked to pull him back but the Australian finished with clear daylight between him and his rivals.
Speaking after his win, Ewan said: "I think it was maybe the last six or seven laps it started to rain a bit which made it a bit more nervous in the bunch. But we were in a great position, my team did a great job to help me stay up the front there because there was a lot of fighting for position. Roger [Kluge] left that gap for me in the final straight there and that gave me a really great launchpad.
"I start this season with a bit of pressure to replicate what I did last year so I'll try and grow my wins on top of that."
The men's Tour Down Under begins on Tuesday January 21, with Ruth Winder (Trek-Segafredo) already sealing the overall victory in the women's race.
Tour Down Under Schwalbe Classic Criterium, Adelaide (51km)
1. Caleb Ewan (Aus) Lotto-Soual, in 1-04-29
2. Elia Viviani (Ita) Cofidis
3. Simone Consonni (Ita) Cofidis
4. Jasper Philipsen (Bel) UAE Team Emirates
5. Kristoffer Halvorsen (Nor) EF Pro Cycling
6. Alberto Dainese (Ita) Sunweb
7. Michael Mørkøv (Den) Deceuninck - Quick-Step
8. Sam Welsford (Aus) Australia
9. Chris Lawless (GBr) Ineos
10. Giacomo Nizzolo (Ita) NTT Pro Cycling, all at same time
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