Internazionale extended their Serie A lead after beating rivals Milan while Roma edged out Udinese.
Inter secured bragging rights in the city of Milan following a thrilling 4-3 success over their near-neighbours.
Things began well for Roberto Mancini's league leaders with Hernan Crespo heading Inter in front, with Dejan Stankovic's rasping drive making it 2-0.
Milan tried to stem the tide with a triple change at the break, however, Zlatan Ibrahimovic's emphatic finish minutes after the restart put the visitors in firm control of the contest.
However, Milan struck back and Clarence Seedorf's deflected shot pulled one back, although that proved a false dawn as Marco Materazzi netted with a powerful header.
The former Everton defender, who is never far from controversy, was then foolishly sent off for collecting his second yellow card for pulling his shirt over his head in the celebrations.
Alberto Gilardino did pull one back for the Rossoneri after 76 minutes and while Kaka added a third in injury time, the 10 men held out to extend their lead at the summit of the table.
Roma have moved into third in Serie A with a 1-0 away win over 10-man Udinese at Stadio Friuli.
Former Everton man Matteo Ferrari put the visitors in front after 66 minutes, a lead they would not relinquish.
Any hopes Udinese harboured of getting back into the match ended when Sulley Muntari saw red.