Napoli 'keeper Pepe Reina ended Mario Balotelli's career streak of 21 successive penalties but failed to see his side reclaim top spot on Sunday despite a first away league win over Milan in 27 years.
Napoli's 2-1 win was their first Serie A victory over the Rossoneri at the San Siro since a side led by Argentine legend Diego Maradona beat Milan in April 1986.
But despite Rafael Benitez's men dominating Massimiliano Allegri's injury-hit side, the Azzurri failed to hold on to the two-goal lead that would have seen them reclaim top spot after Balotelli reduced the arrears in injury time.
It meant Roma, who scored second-half goals through Federico Balzaretti and Adem Ljajic to secure a 2-0 win over derby rivals Lazio, remain top thanks to superior goal difference.
Napoli, in second, also have 12 points with both sides now owning a two-point cushion on Inter, Fiorentina and Juventus after their respective wins over Sassuolo, Atalanta and Verona.
Napoli started in positive fashion and opened the scoring after just six minutes when Miguel Britos headed home Raul Albiol's headed delivery from Jose Callejon's free kick on the left.
Six minutes later Balotelli saw a well-struck free kick go a metre wide of Reina's goal and Milan's woes continued minutes after the restart when goalkeeper Christian Abbiati failed to hold a rocket from Gonzalo Higuain despite the Argentinian falling to the ground as he struck with his right foot.
Barely 10 minutes later Balotelli was fouled in the area but despite being unbeaten in 21 previous attempts for club and country in his career, he saw his spot-kick effort stopped by Reina.
"Winning here after 27 years was extra motivation for us and we're super happy to have achieved this feat," said Reina, who played down his penalty stop.
"Like all goalkeepers, I practise penalty stops in training and I study my opponents."
Milan spurned two chances to reduce the arrears, Reina rushing out to deny Alessandro Matri after Balotelli's cross and then Balotelli seeing his strike under pressure come off the Spanish keeper's crossbar.
Balotelli tested the 'keeper again on 71 minutes with a dipping effort which Reina spectacularly tipped over.
Balotelli finally beat Reina when, in the first minute of injury time, he sent a curling shot from the edge of the area past the Spanish keeper at his far post.
Milan pressed for an equaliser but fell to their second reverse of the campaign and remain 11th, eight points adrift of Roma and Napoli.
To add to their woes Balotelli saw red after the final whistle when he received a second yellow card for dissent.
Milan coach Allegri, however, remained upbeat.
"We played our best game of the season so far," whose side suffered an opening day reverse away to Verona, beaten Cagliari 3-1 at home and scraped a 2-2 draw away to Torino last week.
"In Turin we played well and were lucky. Tonight, luck wasn't on our side."
Despite Roma's positive start to the campaign, coach Rudi Garcia was quick to play down their title hopes.
"We can't forget Lazio were in action three days ago (in the Europa League) and sooner or later you pay for those efforts," said the Frenchman.
"But it was a crucial win for us. Our aim is for a top five finish and a place in Europe but it's far too early to be making predictions."
Fernando Llorente's winner for Juve against Verona was praised by coach Antonio Conte, but he heaped more praise on Carlos Tevez after a superb performance by the Argentinian.
"He's very important because when we're in danger he can keep the ball and create openings for us. It's difficult to do without a player like him,"said Conte.
Earlier, Argentinian striker Diego Milito scored twice on his return from a seven-month injury lay-off as Inter Milan thumped promoted strugglers Sassuolo 7-0.