Kalidou Koulibaly's 91st minute winner secured all three points for Napoli at the Allianz Stadium and put the visitors within a point of 34-times champions Juventus going into the final four games of the season.
In one of the most hotly anticipated clashes of the season across the continent, it was the travelling side who took control from the early stages, with Lorenzo Insigne smashing an early chance just wide of Gianluigi Buffon's post within a minute. There where further problems for the hosts in the first 10 minutes, as veteran defender Giorgio Chiellini came off with an injury - with Stephan Lichtstenier coming on as his replacement.
The absence of Chiellini immediately took effect with Napoli's front three starting to find pockets of space and test the best defence in the league.
Despite Juventus growing in confidence as the game went on, Napoli continued to threaten, and it was the the visitors' all-time leading scorer Marek Hamsik who had the best chance of the early stages, as his shot narrowly missed Juventus goal.
This tense match-up threatened to reach boiling point, as Mirlam Pjanic picked up the game's fourth booking of the match within 25 minutes, while sets of players from both sides had to be separated in an off-the-ball scuffle.
Napoli looked to have took the lead just before half-time, as Insigne slotted the ball under Buffon, but the experience of Lichsteiner at right back payed dividend, as the Swiss international perfectly time the offside trap and the Napoli forward was denied his ninth league goal of the season.
Maurizio Sarri's side went in at the break looking the better side, but the champions hung on to finish the half goalless.
With Napoli seeing the majority of the ball and Gonzalo Higuain touching the ball just nine times in the first half, Massiliano Allegri had to make changes - and off came Juventus' leading goalscorer as Paulo Dybala and Juan Cuadrado entered the fray.
The Juventus faithful were treated to yet more action at the beginning of the second half, but it was the away stand making most of the noise, as Dries Mertens and Jose Callejon threatened once again, but only to hit their opportunities over Buffon's goal.
The Light Blues continued control possession in the game as the second half went on, but Allegri's men were impenetrable at the back, even in the absence of Chiellini.
The home side almost payed for their lack of attacking influence on the game, as Callejon struck the ball on the volley from a sensational Hamsik pass on 70 minutes, only for veteran keeper Buffon to palm the ball away.
Juventus began to show second place Napoli why they are on course for their seventh consecutive Scudetto, as their stubborn defence continued to prevent Napoli from scoring only the 20th goal against the league leaders this Serie A season.
However, this title race for the ages took an almighty twist, as finally, Napoli beat the best defence in the league through Koulibaly on the 91st minute. The Senegalese international rose highest from a Callejon corner, to blast his header past the Italian between the sticks.
Allegri's men battled until the last few seconds, but the defending champions left it to late and payed the price.
Koulibaly's fifth goal of the season was enough to get Napoli over the line to get within just a point of Juventus and ensure only the Old Lady's second defeat at home in 54 matches.
This incredible title race is well and truly on after Napoli's late goal, as Juventus must travel to San Siro to play Inter and the Stadio Olimpico to face Roma.