After a slow start to the first half, Kevin De Bruyne twice attempted to add to his goal against Sassuolo last weekend, firstly finding only the arms of Caprile with a free kick, shortly before putting the ball over with an ambitious strike from the edge of the box.
Caprile did have some work to do before half-time though, as he denied Lorenzo Lucca and Scott McTominay with brilliant saves as the ball looked to be heading into the bottom corner.
The visitors ended the first half without a shot on target themselves, although Matteo Prati came fairly close to scoring with a header that flew just over.
That might have acted as a warning for Napoli, but they emerged from the dressing room with the attitude of champions, and Caprile was called into action again shortly into the second half, keeping out Frank Anguissa’s long-range effort after he latched onto a rebound.
Caprile was having the game of his life, as he then saved wonderfully from Leonardo Spinazzola on the hour mark.
Undeterred, Napoli kept pushing for the breakthrough as Matteo Politano produced a lovely piece of skill before striking just over the bar, but it was starting to look desperate for the Scudetto holders.
Noa Lang finally managed to get the ball past the spirited Caprile, but his goalbound effort was cleared off the line, leaving the hosts surely thinking it was just not their night.
However, Napoli had one last push in them, and in the final minute of stoppage time, they found the breakthrough, as Alessandro Buongiorno squared to Anguissa, who showed remarkable calmness to slot the ball into the net and send the home crowd wild.
The last-second nature of Cagliari’s capitulation adds further spice to a painful stat, where the Sardinians have now won just once in 11 Serie A away outings. As for Napoli, they’ll be relieved to say the least, having secured a third perfect two-game start in four title defences.
Flashscore Man of the Match: Frank Anguissa (Napoli)