Goals from Gonzalo Higuain and Jose Callejon sent Napoli top of Serie A after they beat Atalanta 2-0 on Saturday while an injury-time Mario Balotelli penalty helped AC Milan come from two goals down to snatch a 2-2 draw at Torino.
A superb equaliser from Arturo Vidal earned Juventus a 1-1 draw at Inter Milan in the day's early game, an intriguing Derby of Italy which suggested Walter Mazzari's Inter side could challenge for the title this season.
Walter Mazzari's Inter took the lead against reigning champions Juventus on 73 minutes through Mauro Icardi's first goal for the club, but the away side equalised through Vidal two minutes later.
Napoli maintained their 100 percent record to move to nine points, while Inter and Juve are two points behind and Milan are in sixth place with four.
Argentine Higuain's second goal of the season came in the 71st minute of Napoli's tense match with Atalanta, in which Rafael Benitez's side struggled to break down the away side and had a flying Pepe Reina save to thank for not going behind to German Denis' long-range effort two minutes after the break.
The hosts started quickly, but after Goran Pandev failed to convert an easy looking chance in the 13th minute they laboured and it took until the introduction of Jose Callejon and Marek Hamsik midway through the second half for Napoli to take charge.
Hamsik's aggressive pressing led to the opening goal, with the ball falling to former Real Madrid striker Higuain who rolled home a calm finish.
"For me the important thing is that Marek Hamsik is a Napoli player. He came off the bench and made the difference today," said Benitez, who also praised Callejon's display.
"His movement is different to (Lorenzo) Insigne's, who is different to (Dries) Mertens, Pandev or Hamsik, so we have these five players who can do something different and that gives me something to work with as a coach."
It was Callejon who sealed the three points with his third goal in as many games, another composed strike following neat play from Insigne and Blerim Dzemaili, who back-heeled a delightful assist to the Spaniard.
Milan looked down and out 71 minutes into their clash with Torino, after two superb goals from Danilo D'Ambrosio and Alessio Cerci.
Brazilian Kaka disappointed on his return to the Milan midfield after his move from Real Madrid, barely making a dent in the Torino defence before being substituted a minute before Cerci struck, and will have to up their game with for the Champions League visit of Celtic on Wednesday.
"I'm not worried at all. There's things that need sorting out just like last year there were things that need sorting out," said Milan boss Massimiliano Allegri.
It was a bizarre Sulley Muntari goal eight minutes from time, in which the midfielder scuffed a shot past out-of-position Torino keeper Daniele Padelli, which brought Milan back into the match.
As Milan players celebrated no-one appeared to sure if the goal had even been awarded, with Balotelli both looking offside and seemingly having fouled Padelli in the build up to the goal.
Italy striker Balotelli atoned for missing an easy chance in the 74th minute when he stepped up to slot home the equalising spot kick deep in stoppage time and snatch an unlikely and undeserved point.
After Icaro had fired Inter ahead following fine work from Ricky Alvarez, Juve secured a point when Vidal expertly controlled Kwadwo Asamoah's drilled cross before clipping past Inter keeper Samir Handanovic for his third goal in as many games.
Image: Gonzalo Higuain
Photograph: Giuseppe Bellini/Getty Images