The fourth-placed Milan are on an unbeaten streak of four and could make up further ground on the likes of Sampdoria and Roma with victory at San Siro.
A wretched campaign last term means Milan are free of European commitments this season - something that could play a key role in determining Sunday's outcome.
While Milan will have had a week to prepare for the match, Fiorentina's own continental exertions - which saw them beat PAOK 1-0 on Thursday - leaves them with little time to focus on the Italian giants.
New Milan coach Filippo Inzaghi has his side playing an attacking brand of football - evidenced by the fact they have scored 16 league goals in seven games this term.
"With commitment, work and desire we can do everything," Poli told Milan Channel.
"Against Fiorentina it will already be a fundamental match.
"There's a positive spirit [in the camp]. After a season like the one last year, it has to be like this.
"We come off the back of a negative year, but there's a desire for revenge and to do well.
"The spirit will take us through this year. We want to continue like this.
"We're now expecting a fundamental match against a very strong rival which has to be approached with the right determination and that will say a lot about us."
As a result, they have taken just nine points from their first seven matches this season.
