While Démare's impressive sprint up the slight kick saw him take a second victory at this year's Giro by several bike lengths, Team Sunweb's Matthews remained sanguine.
"It was hectic as we all expected," the Canberran said. "The team did a great job to position us guys that were going to the final into the last 4km.
"Quite a steep uphill for about 800m and from then on it was chaotic sprinting as always.
"I had to take a few risks to be able to stay up there but I think in the final I had some good legs to do the sprint."
"Unfortunately (I) wasn't on Démare's wheel when he started his sprint but was able to come around for second place and making our way to that stage win."
EF Pro Cycling's James Whelan was in the day's break for some 160kms, jumping away with Marco Frapporti (Vini Zabù-Brado-KTM) Mattia Bais (Androni Giocattoli-Sidermec0 and Filippo Zana (Bardiani-CSF-Faizanè) in the opening 10 kilometres.
The Australian eluded the chasing peloton until 14kms from the finish but not before attacked his breakaway companions halfway up the final climb quickly gaining a lead of around 50 seconds.
Démare moved into the maglia ciclamino points jersey with his Stage 6 win.
