Nicola Amoruso's late penalty earned Parma a point as their strong showing following last season's promotion continued.
Napoli had led through German Denis' first-half strike but a foul by Salvatore Aronica, deputising for the suspended Leandro Rinaudo, on Davide Lanzafame allowed Amoruso to level matters with four minutes remaining.
The result took Parma to 24 points and meant they have still only been beaten once at home in advancing to fifth place on their return to the top flight.
Napoli are just four points worse off but drop to 11th place as a result of the late setback.
They started brightly and veteran Parma defender Christian Panucci had to react sharply as Marek Hamsik ran onto German Denis' long pass and crossed, Panucci putting the ball safely behind with Fabio Quagliarella lurking.
The hosts responded with an attack of their own as Lanzafame teed up Francesco Lunardini, whose first-time left-foot effort flashed narrowly wide.
Quagliarella was next to threaten from long range, but his fine right-foot drive was just wide of keeper Antonio Mirante's right-hand post and the danger dissipated.
Mirante was forced into his first meaningful action from Napoli's next attack as the visitors firmly took the upper hand. Hamsik threaded in Christian Maggio and the winger's low drive from a narrow angle was blocked by the keeper.
But Napoli took a deserved lead in the 32nd minute as Maggio surged down the right flank and crossed for Denis to finish neatly past Mirante with his right foot.
That was the way it stayed until the interval but Parma, seemingly galvanised by coach Francesco Guidolin's half-time words, came out with a renewed purpose.
Blerim Dzemaili threatened with a free-kick within three minutes of the restart, his right-footed shot giving keeper Morgan De Sanctis - a virtual spectator in the first half - his first real test.
Paolo Castellini then delivered a dangerous corner which was met by Alessandro Lucarelli, but the centre-half could only head straight at the experienced De Sanctis.
The Napoli defence held firm for much of the half, forcing Lanzafame to chance his arm from 30 yards to draw a decent low save from De Sanctis.
And the visitors could have grabbed a second against the run of play after Mirante's miscued clearance. Hamsik gathered the loose ball and advanced into the box, but Lucarelli was alert and blocked his shot behind for a corner.
And the defender's efforts were rewarded when Lanzafame was brought down in the penalty area by Aronica. The latter escaped punishment for the challenge but team-mate Mirko Contini's over-the-top protests earned him a straight red card.
Amoruso kept his nerve after the delay to slot home from 12 yards and earn his side a share of the spoils.
