The Orobici had a terrible record in this fixture, losing three in a row, but Saturday night's 1-0 result was their first win here since 2008.
"One always hopes, even if the task is tough," said Colantuono.
"The team played just the way we'd prepared it and after a difficult start we gained courage, taking control of the midfield.
"We feared Kevin-Prince Boateng for his movement and were able to limit him very well. The team was balanced, especially with Cristian Raimondi giving us a big hand by tracking back.
"I have to compliment my lads for their organisation on the field against a superior team like Milan."