Inter lead the standings on 42 points with AS Roma, who thrashed third-placed Palermo 4-0 thanks to two goals each from Francesco Totti and Brazilian Mancini, seven points behind.
Italy defender Materazzi fired Inter ahead in spectacular fashion in the 49th minute with an acrobatic overhead kick.
Sweden striker Ibrahimovic then wrapped up the victory 10 minutes later when he finished coolly after a superb run down the flank from Maicon.
The ninth consecutive Serie A victory breaks the club record that had lasted since the 1939-40 season.
Palermo's title challenge faded further with their heavy defeat to Roma at the Olympic stadium leaving them 11 points adrift in third place.
Roma took the lead a minute before halftime when Totti set up Mancini who drove home a 20 metre shot to give Luciano Spalletti's side the advantage at the break.
Totti doubled Roma's lead with a 56th minute penalty after Palermo defender Antonio Pisanu was ruled to have pulled back Brazilian winger Rodrigo Taddei.
Taddei then set up Mancini for Roma's third before the visitor's had Fabio Simplicio sent off in the 87th minute for a second bookable offence.
In the first minute of injury time Totti crowned an impressive Roma display with a deflected shot from the edge of the area to make it 4-0.
Rome's other club Lazio were held to a 1-1 draw at Livorno, a Cristiano Lucarelli goal cancelling out Goran Pandev's opener for the visitors.
Lazio striker Tommaso Rocchi was sent off on the hour for a late challenge and will miss Wednesday's game against Inter.
On Saturday, AC Milan's Alberto Gilardino and Fiorentina's Adrian Mutu scored two goals apiece as their teams drew 2-2.
Gilardino's equaliser a minute from the end earned a point for Carlo Ancelotti's side who nonetheless remain well outside the title race down in 14th place on just 14 points.
