Pato pulled a leg muscle during Milan's 2-0 Champions League win over French side Auxerre on Wednesday.

He will be sidelined for around three weeks but Allegri does not intend to change his tactics.

"Changing things would be a mistake. We can try and find a different solution to adapt to but we'll keep going down the path we took on July 20," Allegri said on Friday.

"Zlatan Ibrahimovic will be our point of reference up front. He will guarantee us a jump in class with his strength and technique."

Brazilian duo Ronaldinho and Robinho are expected to play on the flanks in a three-pronged attack.

Milan crushed Lecce 4-0 before suffering a shocking 2-0 defeat at promoted Cesena in their first two Serie A games.