Giacomo Raspadori scored an 88th-minute winner as Napoli beat Juventus to move closer to a European spot in Serie A.
Victor Osimhen saw a late penalty saved by Wojciech Szczesny, but Raspadori was the quickest to follow it up.
Federico Chiesa looked to have salvaged a draw for Juventus after scoring in the 81st minute, as his low strike found the bottom corner.
A deflected Khvicha Kvaratskhelia volley had earlier put Napoli in front.
Juventus, playing for the first time since Paul Pogba’s four-year ban for a doping offence was confirmed, missed chances of their own as Dusan Vlahovic hit a post with a chipped effort.
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Defeat means second-placed Juventus are 12 points adrift of leaders Inter Milan, who have a game in hand against Genoa on Monday.
Napoli manager Francesco Calzona is yet to lose a game in his four-game tenure at the club since replacing Walter Mazzarri, with this his first win at the Diego Armando Maradona Stadium.
The current champions are only three points off sixth-placed Atalanta as they look to qualify for a European competition after a poor title-defending season.
Atalanta were earlier beaten by Champions League-chasing Bologna.
Scottish midfielder Lewis Ferguson scored a 67th-minute winner in a 2-1 victory for Thiago Motta’s side that keeps them in fourth, four points above Roma.
Sources: BBC Sport