|Inter still hold their position at the top thanks to AC Milan's loss to Palermo [AFP]
Jose Mourinho's Inter Milan were held to a 1-1 draw at Atalanta after being reduced to 10 men when Wesley Sneijder was sent off for a second yellow card on 65 minutes.
City rivals AC Milan failed to capitalise on the result when they were beaten 2-0 at home by Palermo.
Mourinho, who was serving a touchline ban, watched from the stands as the defending champions Inter went ahead after 15 minutes through Diego Milito.
Atalanta made the most of playing against 10 man Inter by snatching a point on 81 minutes through a Simone Tiribocchi equaliser, although they still drop into the bottom three.
The draw was still enough for Inter to extend their lead at the top, though, as Milan suffered at the hands of Palermo at the San Siro.
Simone Tiribocchi fired home the equaliser for Atalanta, beating Brazil defender Lucio not long after Sneijder picked up his second yellow for a late tackle.
Milito had put Inter ahead after dribbling around three defenders and Sneijder nearly made it 2-0 when he slammed a free kick against the crossbar in the 33rd, but by the end Mourinho had little to smile about from his spot in the tribune.
Second-placed Milan slipped five points behind Inter when Fabrizio Miccoli scored one goal and helped set up Mark Bresciano for the second in Palermo's deserved win.
Milan were unable to take advantage of a couple of well-placed crosses from Ronaldinho.
Milan also struggled in a 1-1 draw with FC Zurich in the Champions League this week.
"Handling fatigue with all these games is never easy," Milan coach Leonardo said.
"Today we weren't at the same level as the last few games...We didn't play poorly but we came up against a Palermo side that played better."
Inter lead with 36 points, Milan are second with 31 and third-place Juventus have 30.
Parma are fourth with 28 points after beating 10-man Bologna 2-1 with an 86th-minute winner from Nicola Amoruso, who had earlier missed a penalty.
They move two points behind Juventus who lost 3-1 against Bari on Saturday.
AS Roma and Sampdoria are next with 25 points each following a 0-0 draw in the late match.
Fiorentina followed their victory over Liverpool with a 2-1 loss at Chievo Verona.
Lazio beat 10-man Genoa 1-0 a day after 5,000 of the club's fans protested over the team's poor performance, while Livorno edged 10-man Catania 1-0, with Tomas Danilevicius scoring a late goal to spoil Sinisa Mihajlovic's debut as coach of the Sicilian club.
Siena held on for a 2-1 win over Udinese, who were without Serie A top scorer Antonio Di Natale.