History would suggest that opportunities for Napoli to win the Scudetto come about once every generation - and for much of the afternoon it looked as though any chance of catching Juventus had gone.
Chievo frustrated Napoli for 89 minutes and it was Chievo who from nowhere opened the scoring in the 72nd minute through substitute Stepinski. Napoli pushed hard and it wasn't until the 89th minute that they finally breached Chievo's goal with Arkadiusz Milik finding the net.
Things got even better for Napoli in the 93rd minute when Diawara curled home from inside the box to spark pandemonium at the Stadio San Paulo.
Chievo have showed good defensive endeavour so far this season and did well to frustrate Napoli in the first half, upsetting the tempo of Napoli's play and drawing a number of cynical fouls, whilst Tomovic was also in inspired form at the back.
However, the first chance of the half did fall to Napoli when Insigne, who looked the most dangerous player on the pitch, crossed well to the far post before Callejon blazed over the crossbar from close range.
As the first half wore on, Chievo drifted deeper and deeper, inviting on pressure from Napoli as the team from Verona struggled to gain a foothold in the game - with so few spells in possession, Chievo looked at risk of tiring.
Napoli then looked to have had the perfect start to the second half when in the 50th minute Mertens was dragged down in the penalty area following a lovely one-two with Callejon. Mertens stepped up to convert but his although his penalty was struck well, Chievo stopper Sorrentino saved well.
Napoli will feel aggrieved that Chievo right-back Depaoli avoided a second yellow following the penalty decision, but things almost got a lot worse as Napoli found the ball in their own net 10 minutes later, only for the goal to be adjudged offside.
It was in the 63rd minute that Maurizio Sarri decided to mix things up, bringing on the more physical presence of Milik and the substitution almost immediately paid off when Milik was sent through on goal - but Sorrentino was quick of his line to deny him.
Napoli's hopes of a first Scudetto since 1990 seemingly slipped away after an unlikely goal from Chievo in the 72nd minute. Giaccharini, who did well to intercept Koulibaly's misplaced pass, played the ball across the box and Stepinski duly converted.
However, Napoli were far from finished and kept on pushing numbers forward, intent on getting back into the game, and in the 89th minute Napoli finally found the breakthrough.
Lorenzo Insigne hit a diagonal ball from deep which Milik met with his head at the far post - leaving Sorrentino helpless.
Four minutes of added time were met with frustrated moans from the home support, but three minutes later the groans turned into screams of joy, as Diawara received the ball midway within a packed Chievo box and somehow found the far corner with a sumptuous finessed finish.
Napoli XI: Reina; Hysaj, Tonelli, Koulibaly, Rui; Allan, Diawara, Hamsik; Callejon, Mertens, Insigne.
Chievo XI: Sorrentino; Depaoli, Tomovic, Bani, Gobbi; Bastien, Radovanovic, Rigoni, Giaccherini; Meggiorini, Inglese.