Milan moved closer to a first Serie A title triumph in 11 years thanks to a late strike from Rafael Leao in Sunday's 1-0 home win over Fiorentina.
Inter's shock 2-1 loss to Bologna in midweek handed the Scudetto initiative to Milan and the Rossoneri just about took full advantage with this third league victory in a row.
The visitors had lost three games in a row in all competitions but frustrated their table-topping opponents until Leao made the most of an error to fire in an 82nd-minute winner.
That strike was enough as Milan moved five points clear of Inter, who travel to Udinese later on Sunday. Should it come to it, the Rossoneri boast the better head-to-head record.
Theo Hernandez had an early goal ruled out for an offside infringement against Junior Messias in the build-up in what turned out to be a frustrating contest for Milan.
The hosts probed away without regularly testing Pietro Terracciano, with Olivier Giroud clipping the ball wide when played through from the pick of their first-half chances.
Fiorentina, who are battling for a top-six finish, had some promising opportunities themselves and did at least force Mike Maignan into a save through Riccardo Saponara's shot.
But the best openings continued to fall Milan's way, with Leao slipping when firing over from a glorious position.
Milan needed Maignan to keep out an Arthur Cabral header from point-blank range and that proved a huge moment as Leao's winning goal arrived soon after.
Terracciano mishit his kick from the back and Leao brought the ball inside before calmly curling home to spark jubilant scenes.