© AP Photos
Three minutes later Stephan El Shaarawy got past four Fiorentina defenders to shoot just over the crossbar.
El Shaarawy almost replied immediately for Fiorentina, but failed to find the target from the edge of the area.
The Brazilian striker himself stepped up to take the spot kick but could only shoot over Emiliano Viviano's crossbar.
The Rossoneri started the second half brightly and almost halved the deficit on 50 minutes when Montolivo's header from close range went just wide.
Ten minutes later Giampaolo Pazzini pulled one back for Milan when he slammed home from just yards out after Mexes's backheel had come off the post.
Fiorentina almost made it 3-1 in the 86th minute when substitute Mattia Cassani hit the post with only Abbiati to beat.
That did not affect the Viola much though, as just a minute later Mounir El Hamdaoui wrapped up the points for his side with a curling effort from the edge of the box.