Inter moved a point behind Milan after Romelu Lukaku's penalty earned them victory against Napoli, who finished with 10 men.
Inter closed the gap at the top of Serie A as Romelu Lukaku's penalty sealed a dour 1-0 victory over 10-man Napoli at San Siro on Wednesday.
With local rivals Milan held to a 2-2 draw at Genoa, the Nerazzurri reduced the league leaders' advantage in the standings to one point thanks to Lukaku's 73rd-minute spot-kick.
A rash challenge from David Ospina enabled the Belgium striker to wrap up a fifth straight league win for Inter, and with Lorenzo Insigne seeing red for dissent there appeared to be no way back for Napoli.