Mauro Icardi earned Inter Milan a point from Tuesday night's Derby d'Italia but the 1-1 draw leaves Juventus vulnerable to predators in the Serie A title race.
The Bianconeri had earlier watched Roma draw level with them at the top of the table following a victory at Udinese and set about making amends through Carlos Tevez and his early goal in Turin.
But Inter grew into the game after the break and might even have built on Icardi's equaliser had Mateo Kovacic's dismissal not upset their rhythm in what were frantic final exchanges.
The point gave the Bianconeri control of first place for the time being but rivals Roma show no signs of easing off in their quest to win a first Scudetto since 2001.
Indeed earlier, Roma edged Udinese 1-0 at the Friuli stadium to go one point behind Juve at the top of the table.
Davide Astori headed in the only goal of the game in the 17th minute with the Roma defender's effort hitting the crossbar and falling inside the line before bouncing out.
Udinese demanded a penalty with five minutes remaining -- when Panagiotis Kone fell in the box following a clash with Urby Emanuelson -- but the referee waved play on.
And the hosts almost denied Roma all three points at the death when Danilo got behind Silvan Widmer's pass but his right-footed shot from 10 yards was saved by Roma goalkeeper Morgan De Sanctis.
AC Milan were handed a stark reminder of how much work they still have to do to return to the upper echelons after Sassuolo claimed a famous 2-1 victory at San Siro.
Filippo Inzaghi's men harboured aspirations of climbing into the European places on Tuesday and Andrea Poli put them on the right track in the early exchanges with his first goal of the season.
Ambitious visitors Sassuolo were in no mood to roll over, however, and two assists from Domenico Berardi helped Gianluca Sansone and then, after the break, Simone Zaza to turn the game around.
The surprise result leaves seventh-placed Milan two points shy of the last Europa League berth while Sassuolo -- in only their second top-flight campaign -- climb into the top half of the table.
Napoli followed up their Supercoppa victory over Juventus with a convincing 4-1 win over bottom side Cesena at the Stadio Dino Manuzzi.
On their return to league action they dominated the first half in Emilia-Romagna and well-taken goals from Jose Callejon and Gonzalo Higuain meant Cesena faced a tough task after the break.
Marek Hamsik pushed Napoli three goals clear before Higuain converted his second. Cesena did pull a goal back through Franco Brienza, but at full-time they found themselves seven points shy of safety.
Genoa recovered from going two goals behind to pick up a point from a 2-2 draw with Atalanta at the Stadio Luigi Ferraris.
Davide Zappacosta's first goal in Serie A and a Maximiliano Moralez effort put Stefano Colantuono's men in command in Liguria.
Iago Falque pulled a goal back from the penalty spot soon after before Alessandro Matri netted his first goal at the Marassi to earn the high-flying hosts a point.
Gianfranco Zola endured a difficult start to life as the new coach of Cagliari in the shape of a 5-0 defeat at Palermo.
Cagliari, who lost captain Daniele Conti to a second yellow card in the 26th minute, trailed 3-0 at half-time thanks to goals from Michel Morganella, Ezequiel Munoz and Paulo Dybala.
Dybala struck his second of the afternoon in the 72nd minute before Edgar Barreto capped a wonderful start to 2015 for the Sicilian club by scoring his team's fifth.
Cagliari lost for the ninth time this season to remain in the relegation zone. Palermo, meanwhile, extended their unbeaten run to nine games to climb to eighth in the standings.
Chievo and Torino shared the spoils in an uneventful 0-0 draw in Verona.
The hosts were the better side but could not make the most of their chances and had to settle for a point. The result at the Marc' Antonio Bentegodi stadium lifted Chievo up to 16th place, five points clear of the drop zone.
Empoli held Hellas Verona to a goalless draw at the Carlo Castellani stadium to extend their unbeaten run to six games.
The Tuscan outfit dominated possession but lost defender Lorenzo Tonelli to a second yellow card in the 65th minute and could not find a way through. Verona also struggled in front of goal and finished the game down to 10 men after Emil Hallfredsson was handed his marching orders with 13 minutes remaining for a second booking.