The Frogs are set to play as guests to the reigning league champions in a matchday four fixture at Allianz Stadium.
Sassuolo will be facing a team that has picked full points in all three games played thus far in Serie A.
"Juve is a very dangerous team for everyone," Duncan said at a press conference.
"We are in a positive moment and we are going to Turin to try to continue with our performance and results.
"We'll go there with humility and be compact. We know what our qualities are, we must try to do what the coach asks us."
While Juve currently hold the top spot on the league table, Sassuolo are not faring badly either as two wins and a draw see them in third position, two points adrift of the Old Lady.
"The table looks good. We certainly like being up there," Duncan said.
"We are only in the early stages but seeing ourselves there is beautiful.
"It must give us the awareness that we can do a lot. We must continue like this and then see where we finish."
Having lasted for the entire duration of all three Sassuolo games played thus far, Duncan will be expected to play a crucial role on Sunday, alongside compatriot Kevin-Prince Boateng, who is tipped to lead the attack.