Before the Bianconeri ran out 2-0 winners at the San Siro against Milan, their Champions League opponents this Tuesday had managed to secure their own victory away from home.
An 89th-minute goal by Bas Dost saw Sporting CP overcome Rio Ave 1-0 on Friday night to stay within two points of Portuguese league leaders Porto, who beat Boavista 2-0.
Meanwhile in La Liga, there was no letting from first-placed Barcelona, who triumphed away to Athletic Bilbao thanks to a first-half strike from Lionel Messi before Paulinho wrapped up the victory in the 90th minute.
The Blaugrana remain four points clear of nearest challengers Valencia, who made sure of winning 2-1 away to Alaves.
The only Group D team not to win at the weekend, however, was Olympiacos. The Athens club lost 1-0 to intercity rivals Panathinaikos – a result that leaves them in fifth place and five points off the top in the Greek Super League.