Abbiati made a string of excellent saves to limit the home side to just two goals, with Allegri quick to point out the impact of his shot-stopper.
"Abbiati made some great saves, particularly in the first half but also in the second," UEFA.com quotes Allegri as saying.
"He is a great goalkeeper, he made some mistakes early in the season but it's normal. Everybody makes mistakes but when the goalkeepers make them it's obvious to anybody.
"However, he has proved during his whole career how good he is and tonight he confirmed it."
The result puts Milan top of Group C until at least the conclusion of Malaga's game against Anderlecht.