The Danish midfielder feels the Amsterdam club's Champions League campaign will depend on sealing maximum points on Tuesday after its loss to Barcelona.
The Eredivisie champion was beaten 4-0 by Barcelona on matchday one, whereas Milan recorded a 2-0 win over Celtic, and Poulsen has warned his side to seal maximum points at the Amsterdam ArenA in order to keep the team's chances of progressing alive.
"It's hard to make a prediction, but what I do know is that we really need a good result. That's the only way we can achieve something in this group," Poulsen told Goal. "If we want to progress, we must beat AC Milan. Getting a good result against Milan also shows that we have ambition.
"Milan are a completely different team than a few years ago. They have many more young players now and have a lot of gifted players in attack. Mario Balotelli is a great player and so is Stephan El Shaarawy. I think he's as good as Balotelli."
El Shaarawy was expected to make the Milan squad for Tuesday's encounter after a four-week spell on the sidelines, but he endured a recovery setback on Monday that will keep him out of action.