Lautaro Martinez handed the visitors an early lead when he slotted in after some good work from Romelu Lukaku. AC Milan shrugged off their shaky start and grew into the game. But the erstwhile league leaders were unable to get on the scoresheet.
Following the half-time break, Inter Milan consolidated their advantage to end the game as a contest. Martinez doubled the visitors' advantage near the hour mark, capping off a wonderful team move that included Achraf Hakimi, Christian Eriksen and Ivan Perisic.
Minutes later, Lukaku put the game to bed, scoring his 17th of the campaign to seal all three points for his side.
On that note, here are five major talking points from the match.
#5 Inter Milan move four points clear, but the Serie A race is heating up
With Inter Milan's comprehensive win over rivals AC Milan, the 2020-21 Serie A title race is now wide open.
Antonio Conte's men are now four points clear of their arch-rivals AC Milan. But with reigning champions Juventus having two games in hand and AS Roma, Napoli and Atalanta in the mix as well, this season's title race could right go down to the wire.
#4 Lautaro Martinez regains his mojo
Lautaro Martinez was on fire against the Rossoneri.
The Argentine international scored a brace to secure all three points for his side. His performance against Milan and a week earlier against Lazio indicate that the striker has rediscovered his mojo at a crucial point in the season.
Martinez put in a massive shift up front, causing all sorts of trouble to Milan's backline. He won five duels, made three recoveries and completed two dribbles during his stay on the field.