Carlo Ancelotti's men have struggled to break down the lesser teams this season: they drew with both Lecce and Toro and only just managed to scrape past Chievo 1-0.
Sacchi, who coached at the club between 1987 and 1991, doesn't think Milan have what it takes this term even though they are just three points behind bitter city rivals Inter.
"Milan have an excellent tactical culture. Carlo Ancelotti has been there for seven years but he doesn't always find the equal motivation and determination," Sacchi told La Gazzetta Dello Sport.
"The team has great technical qualities and they are brilliant at holding onto the ball but sometimes they over do it and they fail to find the same hunger and enthusiasm.
"A lot of players move without the ball and they only express their best football in the big games and this could cost them."
"I don't think it will be easy for them to win."
The Rossoneri take on Portsmouth in the UEFA Cup on Thursday night but their main aim this season remains the Scudetto.
Salvatore Landolina, Goal.com