Juventus and Roma took full advantage of Napoli's failure to win on Saturday by putting four past their respective opponents on Sunday.
Serie A leaders Juve were the far superior side as they brushed aside Atalanta 4-1 to maintain their five-point lead over second-placed Roma.
The men from Turin broke the deadlock after just six minutes when Carlos Tevez scored his fourth goal in his last two league games. Atalanta soon levelled through Maximiliano Moralez, who became the first Serie A player to score against Gianluigi Buffon in 745 minutes of football.
But Juventus stepped up a gear after the interval, with Paul Pogba, Fernando Llorente and Arturo Vidal all finding the back of the net.
Roma, meanwhile, stretched their unbeaten league run to 19 with a 4-0 thumping of basement club Catania.
Mehdi Benatia set the ball rolling in the 18th minute before - like Juve - Roma found their stride in the second half.
Mattia Destro and Gervinho added their names to the scoresheet either side of a second Benatia strike to make sure of three points that see Rudi Garcia's men go five clear of Napoli.
At San Siro, Rodrigo Palacio scored a dramatic late winner to seal maximum points for Inter in a derby encounter that heaps further pressure on city rivals Milan.
The Argentine's cheeky flicked finish four minutes from time was swiftly followed by a red card for Sulley Muntari after an altercation with Zdravko Kuzmanovic on another miserable night for Milan coach Massimiliano Allegri.
Defeat leaves them 27 points off leaders Roma and just five point clear of the relegation zone, while Inter leapfrog Verona into fifth.
Fiorentina closed the gap on third place to just three points with a 1-0 victory over Sassuolo, while Verona kept pace with the chasing pack in a convincing 4-1 win against Lazio, who have just one triumph from their last eight league fixtures.
With the goals flying in all over Italy, Torino made it five games unbeaten as they thrashed lowly Chievo 4-1 and Sampdoria held Parma to a 1-1 draw.
At the other end of the table, Alessandro Diamanti scored the only goal as Bologna hauled themselves out of the relegation zone with a 1-0 win against Genoa.