Internazionale ended Napoli’s perfect start to Serie A after holding them to a thrilling 0-0 draw on the road, themselves being the only other unbeaten side in the Italian top flight.
Napoli, who dropped points for the first time this campaign, were the better side but could not find a way past Inter goalkeeper Samir Handanovic, who was kept busier than his Napoli counterpart Pepe Reina.
It was also the first time that Napoli failed to win a Serie A fixture since April but they remain top, two points above Inter and three above Juventus and Lazio.
Inter had plenty confidence after Mauro Icardi’s hat trick helped them win last week’s derby against city rivals Milan, but they hadn’t won in Naples in 20 years.
Starting on the front foot, Napoli almost went in front but Handanovic pulled off a stunning double save to deny José Callejón and then keep out Dries Mertens’ rebound from point-blank range.
Handanovic then added to his saves by palming away Lorenzo Insigne’s close-range header and a powerful drive from substitute Piotr Zielinski.
Later, the Milan club got their first chance went close shortly before half-time but Reina did well to fingertip Borja Valero’s close-range attempt over the bar. Mertens should have won the match for Napoli in the final minute but Handanovic was again on hand to keep out his close-range volley.
Meanwhile, Juventus maintained their distance against the leaders although being reduced to ten-men early on.
Mario Mandzukic was sent off early on as he was shown an instant second yellow card for appealing against a first booking, after Stipe Perica gave Udinese a shock lead.
However, Samir’s own goal levelled for Juve, and Sami Khedira headed Juve ahead even before Mandzukic’s dismissal.
Although Danilo levelled for Udinese two minutes after half-time, Daniele Rugani put Juve ahead again and Khedira scored twice to complete a hat-trick before Miralem Pjanic’s last-minute strike.