Two players with Roma connections, Andrea Bertolacci and Philippe Mexes, were on target as Milan picked up their third consecutive victory thanks to a 3-1 Serie A win at Lazio.
Milan had failed to beat Lazio in their past five visits to Stadio Olimpico but goals from Bertolacci, Mexes and Carlos Bacca settled Sunday's contest, although the win was overshadowed somewhat by concerns for Alex who was knocked unconscious during the second half.
Bertolacci, born in Rome, endured a mixed homecoming. The Italy international, who came through the youth ranks at Lazio's fierce rivals Roma, tapped in the opener after a poor piece of goalkeeping from Federico Marchetti but was forced off injured soon after.
Alessio Cerci also hit the post in a first half dominated by Milan, and the visitors had a second when Mexes, who spent seven years at Roma, headed home the second less than a minute after replacing Alex.
It was a particularly sweet moment for Mexes, who in last season's corresponding fixture - a 3-1 defeat for Milan - was sent off and later hit with a four-match ban for grabbing Stefano Mauri by the throat.
Sinisa Mihajlovic, who won Serie A during a six-year stint with Lazio as a player, then saw his side put the game beyond reach with Bacca's late goal and, although Ricardo Kishna bagged a late consolation, Milan leapfrogged their opponents in the table.
Lazio saw tentative penalty claims waved away in the fifth minute when Lucas Biglia was barged to ground by Riccardo Montolivo.
Milan edged play in the opening stages, though, and Giacomo Bonaventura saw a rasping 20-yard drive narrowly clear the crossbar.
And they took the lead in the 25th minute, albeit with a helping hand from Marchetti.
Alessio Cerci cut in from the right and his left-footed shot was parried straight into the path of Bertolacci, who provided the simple finish.
Milan came desperately close to a second moments later. Montolivo set Cerci free in the right of the area but his curling shot agonisingly rebounded off the far post to safety.
There was a stoppage in play shortly after the restart when centre-back Alex was knocked out cold after being sandwiched between 16-year-old goalkeeper Gianluigi Donnarumma and Juraj Kucka.
When the action restarted, Mexes made a stunning impact as a substitute, leaping highest to head home Bonaventura's excellent whipped free-kick.
Lazio attempted to garner some momentum and Kishna had a goal rightly ruled out for offside when he tapped in at the back post.
But Milan were out of reach with 10 minutes remaining when Bonaventura played in Bacca, who rounded Marchetti to shoot into the unguarded goal.
Lazio restored some pride when Kishna fired home at the near post from the left of the box in the 85th minute, but it was too little too late.
