As the bell rang for the final lap, Van Avermaet made it into a move of around 20 riders where attacks sparked alight from the likes of Tim Wellens (Lotto Soudal), Benoit Cosnefroy (AG2R La Mondiale) and Julian Alaphilippe (Deceuninck - Quick Step).
But the race came back together before the final hairpin turn, the Belgian timing his move on the final kick to the line to perfection, coming round Diego Ulissi (UAE Team Emirates) and Ivan Garcia Cortina (Bahrain Merida) for victory.
Van Avermaet finished Canada's weekend of one-day WorldTour races with today's win and his third-place on Friday's Grand Prix Cycliste de Québec and looks well-placed ahead of the UCI Road World Championships in Yorkshire.
"It’s been a year of top 10 places and podiums but never really a big win in a WorldTour race so I’m super happy to finally get it," he said.
"I knew it would be a close call to stay away or to bring Alaphilippe back. Everything went well in the end. I tried to bridge to Wellens on the last climb, but it was all stretched out with small gaps and luckily everything came back. I knew the finish was good for me and I know that after a hard race like this I still have a good sprint in the end.
"I think (the worlds is) a good course for me and I’m happy with my shape, that’s the most important. We will see how the race goes and what plan we have with the Belgian team.”
A quick glimpse at the top 20 of today's race reveals a cache of riders all capable of winning the men's road race in two weeks including Wellens, Alaphilippe, Michael Woods, Peter Sagan, and encouragingly for Australia, Jack Haig and Friday's Grand Prix Cycliste de Québec winner Michael Matthews.
Absent from this weekend's races was Mathieu van der Poel who put on his own show in a dominant display at the Tour of Britain, winning three stages and the overall title.
If the big teams can't shake the Dutchman by the final circuits in Yorkshire, it is hard to see him not winning the sprint finale, no matter how many or who is in the bunch.
The 2019 UCI Road World Championships features eleven races over eight days in the junior (U19), under 23 and elite categories.
The road races promise to push the world’s best to the limit with a punishing 285km contest for the men and 150km for the women, with both races to culminate with laps of a technical circuit around Harrogate.
SBS will stream selected events from the 22-29 September UCI Road World Championships on SBS OnDemand and the website with live TV coverage of the women's and men's road races scheduled for SBS Viceland.