The Rossoneri lead the Dutch champions in Group H and need just a single point to qualify for the knockout stages, but Allegri has insisted that his side will be doing all they can to ensure a win.
"We have the advantage of being able to get two results out of three," he told Milan Channel.
"But there's a lot at stake. We'll have to be very attentive and we can't just defend the 0-0.
"We have to go into the match with calmness and determination. It's a football match like the others and tomorrow a draw would be the same as a win, but we have to take to the pitch to win."
Barcelona host Celtic in the group's other fixture, with the Spanish side already through to the last 16.