In the final sprint, with a slight headwind to contend with, world champion Peter Sagan led Irishman Bennett out.
But Ewan blasted down the open road on the left-hand-side and timed his kick to perfection, catching Bennett out just as the Bora-hansgrohe man swung off his team-mate’s wheel.
Van Poppel came through to take second place, splitting Ewan and Bennett, but it will be Ewan – for the second consecutive year – who starts stage two with the ochre jersey on his back.
Santos Tour Down Under 2017: stage one – result
1) Caleb Ewan (AUS) – Orica-Scott – 3.24.18hrs
2) Danny van Poppel (NED) – Team Sky – ST
3) Sam Bennett (IRL) – Bora-hansgrohe
4) Marko Kump (SVN) – UAE Abu Dhabi
5) Niccolo Bonifazio (ITA) – Bahrain-Merida
6) Nikias Arndt (GER) – Team Sunweb
7) Baptiste Planckaert (BEL) – Katusha-Alpecin
8) Edward Theuns (BEL) – Trek-Segafredo
9) Miles Scotson (AUS) – BMC Racing
10) Sean de Bie (BEL) – Lotto-Soudal
General classification
1) Caleb Ewan (AUS) – Orica-Scott – 3.24.08hrs
2) Danny van Poppel (NED) – Team Sky +4”
3) Sam Bennett (IRL) – Bora-hansgrohe +6”
4) Jay McCarthy (AUS) – Bora-hansgrohe +7”
5) Nathan Haas (AUS) – Dimension Data +8”
6) Simon Gerrans (AUS) – Orica-Scott – ST
7) Jose Goncalves (POR) – Katusha-Alpecin
8) Marko Kump (SVN) – UAE Abu Dhabi +10”
9) Niccolo Bonifazio (ITA) – Bahrain-Merida – ST
10) Nikias Arndt (GER) – Team Sunweb