Macedonian striker Goran Pandev slotted in a scuffed shot from Samuel Eto'o after six minutes to grab his third goal since rejoining Inter last month.
Defender Walter Samuel then powered in a header from a corner and Argentina's Diego Milito netted his 14th goal of the league campaign after a fine move just after the break.
"We can definitely improve a lot more but I'm happy for the three points. We are only thinking about ourselves, other results don't bother us," Pandev, whose side can extend their eight-point lead at Parma on Wednesday, told Sky TV.
Roma striker Francesco Totti, considering coming out of international retirement for Italy at June's World Cup, went off at halftime after his fitness problems reoccurred.
A fight between fans before kick-off and a scuffle in the players' tunnel marred Antonio Di Natale's hat-trick in lowly Udinese's 3-1 win over fourth-placed Napoli, who had goalscorer Christian Maggio sent off on half-time for diving.
The defeat was Napoli's first in the league for 16 games.
Italy forward Di Natale, Serie A's top scorer with 16 goals, netted early when he knocked in the rebound after his penalty was saved and he made it 2-1 in stoppage time with an acrobatic finish before adding a third.
Sampdoria's 2-1 win at bottom side Siena meant the Genoa club climbed to sixth spot, above free-falling Juventus who drew 1-1 at Livorno on Saturday.
Genoa beat fellow mid-table side Chievo 1-0 and Catania boosted their hopes of survival and left Lazio third from bottom thanks to Maxi Lopez's second-half goal in a 1-0 win in Rome.
