Serie A champions Inter Milan lost ground from leaders Lazio as guests Sampdoria late Sunday forced them to salvage a 1-1 draw, dpa reported.
Samuel Eto'o levelled a goal from Sampdoria's Stefano Guberti to score his seventh goal from eight games, while Inter moved onto 15 points.
Lazio remained top on 19 from a 2-1 win over Cagliari earlier Sunday, with Sergio Floccari and Stefano Mauri on target as the Rome side notched their sixth win.
AC Milan were looking to remain two points adrift when they tackle Napoli late Monday.
At the rain-drenched Giuseppe Meazza, midfielder Guberti volleyed home a cross from Antonio Cassano, who dispossessed Cristian Chivu to square from the right on 62 minutes.
Brazil goalkeeper Julio Cesar was well positioned to block the low shot, but failed to hold on to the ball and saw it bouncing into the net.
Samp goalkeeper Gianluca Curci was called to two first-half saves on breaks from Brazilians Lucio and Coutinho, but after the break was hurt and replaced by Brazilian Da Costa, who stood no chance when Eto'o flicked home a cross from Coutinho with 10 minutes left.
Earlier at the Stadio Olimpico, Floccari in the first half drilled home a precise drive after the Cagliari defence blocked a free kick from Brazilian Hernanes. The captain Mauri found a lucky deflection before Alessandro Matri pulled one back for Cagliari on the hour.
Juventus, meanwhile, slowed down their pace and slid seven points from Lazio when they were held 0-0 at minnows Bologna.
Striker Fabio Quagliarella missed from close range after Milos Krasic dispossessed a defender and Vincenzo Iaquinta squandered a penalty for Juve.
Lowly Chievo snatched a late 2-1 win over newcomers Cesena and leapfrogged Juve into fourth place, Genoa edged Catania 1-0 and Udinese improved after a horrible start to the season when they beat Palermo 2-1 despite the dismissal of Andrea Coda.
Lecce rallied to beat Brescia 2-1 in a clash of promoted sides, while struggling giants Roma were held 0-0 at lowly Parma in a rainy Sunday lunch-time match.
On Saturday, Fiorentina left last place as Marco Donadel and Alberto Gilardino were on target in a 2-0 win over Bari.