Milan need a win to keep their hopes of reaching the Champions League round of 16 alive.
Pioli said: "We are playing an important match, one can use the turning point term for the group. They are a strong team, but they can suffer difficulties, so we have to play with everything we can for 95 minutes.
"I'll just say one thing: we knew the Yellow Wall, but they don't know the San Siro of the Champions League. We do. I'm sure the fans will help us tomorrow night too."
Asked if their win against PSG can be inspiration, the coach said: "That's the reference. We went down, but we remained a team until the end. That must be the mental attitude, then the match will be different because Dortmund is different from PSG."