Milan made short work of Monza with a great Brahim Diaz brace, then Divock Origi’s first goal for the club and Rafael Leao, but Filippo Ranocchia scored a marvellous consolation free kick.
The Rossoneri rotated the squad ahead of the Champions League clash with Dinamo Zagreb, resting Olivier Giroud and Rafael Leao, with Mike Maignan, Davide Calabria, Alexis Saelemaekers, Alessandro Florenzi and Zlatan Ibrahimovic injured. Monza, run by former Milan chiefs Silvio Berlusconi and Adriano Galliani, had won four of their five competitive matches under coach Raffaele Palladino. Armando Izzo and suspended Nicolò Rovella missed the trip, just days after knocking Udinese out of the Coppa Italia.
Brahim Diaz created the opening goal out of nowhere, as he controlled a Ciprian Tatarusanu clearance with a great first touch in the centre-circle and just started running at Monza defenders, prodding in from eight yards while going over under pressure from Antov.
Origi tested Michele Di Gregorio and hit the side-netting, but Tatarusanu made two tough saves by palming the Stefano Sensi scorcher out from under the bar, then parrying a Carlos Augusto free diving header from nine yards.
Milan doubled their lead just before half-time with another Brahim Diaz strike. He gathered an assist from Origi down the right, turned Luca Caldirola and smashed the right-foot angled drive into the far bottom corner.
Brahim Diaz also sent Rebic through to test Michele Di Gregorio one-on-one, but the Spaniard then limped off clutching the back of his left thigh.
Origi finally got his first goal in the Milan jersey, gathering from Junior Messias on the edge of the area and smashing a ferocious right-foot finish into the near top corner.
Monza got one back at San Siro in style, as Filippo Ranocchia bent his long-range free kick around the wall and in at the near post despite Tatarusanu getting fingertips to it.
The visitors threatened another too, Tatarusanu parrying a powerful Carboni strike at the near stick, but Milan added their fourth late on.
Theo Hernandez burst away from Valentin Antov and rolled across for Rafael Leao, who took a touch before blasting in with his right foot from 12 yards. The two teammates celebrated with a Dragonball move.
It should’ve been 5-1 in stoppages, but Charles De Ketelaere failed to connect with the Messias assist alone in front of goal.