Napoli had fought back from 3-0 down thanks to goals from three of its new signings but Kalidou Koulibaly's attempted clearance looped into his own net in stoppage time to give Juventus the win.
MILAN — Juventus won 4-3 Saturday in an Italian league defeat that will hurt southern-based Napoli even more as it was orchestrated by its former coach and one of its former players. Worse still, Juve's winner was an own-goal by Napoli.
Napoli had fought back from 3-0 down thanks to goals from three of its new signings but Kalidou Koulibaly's attempted clearance looped into his own net in stoppage time.
Juventus had appeared to be cruising to an impressive victory after goals from debutant Danilo, former Napoli forward Gonzalo Higuain and Cristiano Ronaldo.
New Juventus coach Maurizio Sarri was at the stadium but not on the bench as he recovers from pneumonia. Napoli fans have labeled him a traitor for taking over their bitter rival after making his name in Naples.
Danilo signed from Manchester City earlier this month and he had an immediate impact 26 seconds after coming on for the injured Mattia De Sciglio, giving Juventus a 16th-minute lead following a rapid counterattack from Douglas Costa.
Juventus doubled its tally three minutes later. Higuain received the ball with his back to goal, swiveled to beat Koulibaly and fired into the top right corner.
Ronaldo netted his first league goal of the season shortly after the hour mark, slotting home after another assist from Costa.
Napoli got one back in the 66th as former Roma defender Kostas Manolas headed in a free kick for his first goal for his new club and debutant Hirving Lozano further reduced the deficit less than three minutes later when he beat Matthijs de Ligt to Piotr Zielinski's cross.
The 20-year-old de Ligt, who became the most expensive defender in Serie A history when he completed a 75 million euro ($85 million) transfer from Ajax last month, had been handed his debut in place of injured Juventus captain Giorgio Chiellini.
De Ligt was also was at fault for Napoli's equalizer as he allowed Giovanni Di Lorenzo to get in front of him and bundle in Zielinski's cross.
However, there was still another twist. There appeared to be no danger when a Juventus free kick was floated into the area, especially with Koulibaly in lots of space to make the clearance, but he shinned it into the top corner of his own net.