The 185 km (115 miles) route, featuring two climbs, offered the perfect day for the GC contenders to stay safe and allow riders in the breakaways to have their day in the sunshine.
And so they did, with the stage coming down to a three-way sprint eventually taken comfortably by Germany's Nico Denz (Bora-Hansgrohe), who got his first Grand Tour stage win.
Latvia's Toms Skujins (Trek-Segafredo) was second with Australian Sebastian Berwick (Israel-Premier Tech) sitting up before the line to cross in third.
Race leader Geraint Thomas finished several minutes back in the peloton along with the remaining GC contenders.
The fight for the Maglia Rosa will resume in earnest on Friday as the race hits the Alps for the first time this year, crossing the Swiss border with a summit finish at the ski resort of Crans Montana.
Denz was part of a five-rider attack from the front of a large breakaway group with just over 90km remaining.
Italy's Alessandro Tonelli was then dropped near the top of the 9km Colle Braida climb, leaving the trio of Denz, Skujins and Brewick to contest the victory.
On the flat finish in Rivoli, Denz hit the front first and Skujins could make no impression as the German roared in celebration as he crossed the line.
"On the last climb, I was on my very limit. I barely made it over the top," Denz, who grimaced his way up the slopes, said.
"Once I achieved that, obviously everything came back together. I also have quite a fast finish and that saved me in the end. I'm over the moon right now."
