Spanish forward Alvaro Morata put the Italians ahead in the 41st minute and his replacement Simone Zaza sealed the victory with a second goal three minutes from time.
Benfica came from a goal behind to beat Atletico Madrid 2-1 at the Vicente Calderon and go top of Group C.
It was a clinical display of counter-attacking football from the Portuguese champions, who had gone behind after 23 minutes courtesy of an Angel Correa goal for Atletico.
However goals from Nico Gaitan and Goncalo Guedes were enough to seal a victory that sees Benfica maintain their 100% start and leapfrog their Spanish counterparts at the top of the group.
Elsewhere in Group C, Astana became the first team from Kazakhstan to win a point in the group stages of the competition, with a 2-2 draw at home to Galatasaray.
Galatasaray led at half time through Bilal Kisa but Astana drew level as Junior Kabananga took advantage of Semih Kaya’s slip, and his cross went into the net off luckless defender Hakan Balta.
Gala’s hopes were boosted when Eric made a hash of sub Sinan Gumus’ shot four minutes from time and the ball trickled over the line. Colombian midfielder Roger Canas produced an 89th-minute equaliser for the Kazakhs.