Speaking with La Gazetta dello Sport the Republic of Ireland boss, who has managed both Italian giants in the past, expressed his belief that very little stood between the two bitter rivals, but that Massimiliano Allegri's side would narrowly pip the Nerazzurri to the title if they collect the points on Saturday.
"I like Max Allegri, he has been a wonderful surprise," Trapattoni said.
"An illogical team has all of sudden become a title contender thanks to three words: spirit of sacrifice. If Milan want to win the Scudetto they must stop Inter now in the derby.
"If Leonardo overtakes Milan the title race is over. The Nerazzurri would become like those American aircraft carriers that win all the wars - unassailable."
The derby takes place with leaders AC Milan holding a slender two-point lead over Leonardo's men.
A win will place either side in pole position to win the title with just eight games currently remaining in the season.