Viviani, who joined QuickStep from Team Sky in the winter, pounced on a moment’s hesitation from the Australian to burst through and take victory in the scorching Adelaide heat.
The stage has already been shortened due to the extreme temperatures in South Australia, but stage two winner Ewan refused to blame external factors – admitting post-stage he had messed up the sprint despite a great lead-out from his team.
Nevertheless, he still leads overall by ten seconds from Viviani having scooped four bonus seconds for finishing third, with Phil Bauhaus (Team Sunweb) sneaking into second place on the stage.
Despite the soaring temperatures, which led to organisers chopping two laps of the final circuit from the end of the race, Nickolas Dlamini (Dimension Data) and Scott Bowden (UniSA-Australia) continued their 100 per cent record of getting in the break.
Given the rising mercury, which hit 40 degrees, the peloton was happy to let the duo go as Dlamini continued his one-man assault on the King of the Mountains title, but the South African sat up once the day’s climbing was done.
It left Bowden to plough on alone, satisfying himself with the consolation of winning the two intermediate sprints – the passage of which saw a little flurry of action in the peloton with unexpected bonus seconds up for grabs.
Nathan Haas (Katusha-Alpecin) improved his overall position by two seconds at Inman Valley, while Bora-hansgrohe’s Jay McCarthy – third on stage two – snatched the final second.
Bowden was then swallowed up by the bunch with 20km still to ride, affording opportunity for more attacks, but only Tiago Machado (Katusha-Alpecin) tried to seize the initiative.
The Portuguese rider quickly established a lead of 17 seconds, but as soon as the sprint teams organised themselves he was swiftly reeled in.
Mitchelton-Scott put themselves in pole position for another stage win, dropping Ewan in a perfect position, but with the race leader delaying his sprint, Viviani was not to be denied.
Viviani’s success seals a half-century of pro wins, but it remains to be seen if the sprinters will get another opportunity on stage four, with a punchy finale in new stage finish town Uraidla a potential chance to shake up the GC.
Tour Down Under 2018: stage three – result
1) Elia Viviani (ITA) – QuickStep Floors – 3.04.40hrs
2) Phil Bauhaus (GER) – Team Sunweb – ST
3) Caleb Ewan (AUS) – Mitchelton-Scott
4) Simone Consonni (ITA) – UAE Team Emirates
5) Peter Sagan (SVK) – Bora-hansgrohe
6) Simon Clarke (AUS) – EF-Drapac
7) Alexander Edmondson (AUS) – Mitchelton-Scott
8) Zak Dempster (AUS) – UniSA-Australia
9) Dries Devenyns (BEL) – QuickStep Floors
10) Jay McCarthy (AUS) – Bora-hansgrohe
1) Caleb Ewan (AUS) – Mitchelton-Scott – 10.58.36hrs
2) Elia Viviani (ITA) – QuickStep Floors +10"
3) Daryl Impey (RSA) – Mitchelton-Scott +14"
4) Jay McCarthy (AUS) – Bora-hansgrohe +15"
5) Peter Sagan (SVK) – Bora-hansgrohe +16"
6) Nathan Haas (AUS) – Katusha-Alpecin +17"
7) Jhonatan Restrepo (COL) – Katusha-Alpecin +19"
8) Simone Consonni (ITA) – UAE Team Emirates +20"
9) Robert Gesink (NED) – LottoNL-Jumbo – ST
10) Anthony Roux (FRA) - FDJ