Match ends, Juventus 3, Napoli 1.
Juventus made it seven wins in a row at the start of the Serie A season, coming from behind to beat second-placed Napoli and move six points clear.
The visitors led when Dries Mertens tapped into an empty net.
Cristiano Ronaldo had a hand in all three Juve goals, first crossing for Mario Mandzukic to head an equaliser.
He had a shot come off the post, with Mandzukic scoring the rebound - and then Ronaldo flicked a header on for Leonardo Bonucci to score.
Napoli ended with 10 men after Mario Rui was shown a second yellow card, for a foul on Paulo Dybala, with the score 2-1.
Juventus, who are looking for an eighth consecutive league title, rode their luck at 0-0 - with Piotr Zielinski's long-range strike hitting the post for Napoli.
Ronaldo has only scored in two of his eight Juventus games, although he was lively at the Allianz Stadium.
As well as creating all three, he had chances to score himself - with five shots on target.
They have won all eight games this season, including the 2-0 win over Valencia in the Champions League, where Ronaldo was sent off.
Earlier in the day, Roma beat Lazio 3-1 in the capital derby. Lorenzo Pellegrini gave them the lead, with Ciro Immobile equalising.
But former Premier League defenders Aleksandar Kolarov and Federico Fazio netted to give Roma victory.
Match ends, Juventus 3, Napoli 1.
Second Half ends, Juventus 3, Napoli 1.
Foul by Alex Sandro (Juventus).
Allan (Napoli) wins a free kick in the defensive half.
Attempt blocked. Lorenzo Insigne (Napoli) right footed shot from outside the box is blocked.
Attempt blocked. Arkadiusz Milik (Napoli) right footed shot from outside the box is blocked. Assisted by Fabián Ruiz.
Foul by Federico Bernardeschi (Juventus).
Allan (Napoli) wins a free kick in the defensive half.
Attempt missed. Cristiano Ronaldo (Juventus) header from the centre of the box is high and wide to the right. Assisted by Federico Bernardeschi with a cross.
Attempt blocked. Lorenzo Insigne (Napoli) right footed shot from outside the box is blocked.
Foul by Rodrigo Bentancur (Juventus).
Allan (Napoli) wins a free kick in the attacking half.
Offside, Juventus. Blaise Matuidi tries a through ball, but Cristiano Ronaldo is caught offside.
Attempt missed. Lorenzo Insigne (Napoli) right footed shot from outside the box misses to the right. Assisted by Allan.
Alex Sandro (Juventus) is shown the yellow card for a bad foul.
Foul by Alex Sandro (Juventus).
Raúl Albiol (Napoli) wins a free kick in the defensive half.
Substitution, Juventus. Juan Cuadrado replaces Mario Mandzukic.
Attempt missed. Cristiano Ronaldo (Juventus) left footed shot from the left side of the box is close, but misses to the left. Assisted by Mario Mandzukic.
Offside, Juventus. Blaise Matuidi tries a through ball, but Cristiano Ronaldo is caught offside.
Corner, Napoli. Conceded by Alex Sandro.
Corner, Napoli. Conceded by Giorgio Chiellini.
Attempt saved. Cristiano Ronaldo (Juventus) right footed shot from the left side of the box is saved in the centre of the goal. Assisted by Federico Bernardeschi with a through ball.
Offside, Juventus. João Cancelo tries a through ball, but Federico Bernardeschi is caught offside.
Goal! Juventus 3, Napoli 1. Leonardo Bonucci (Juventus) left footed shot from the left side of the six yard box to the bottom left corner. Assisted by Cristiano Ronaldo following a corner.
Attempt missed. Cristiano Ronaldo (Juventus) header from the right side of the six yard box is close, but misses to the left. Assisted by Federico Bernardeschi with a cross following a corner.
Corner, Juventus. Conceded by Fabián Ruiz.
Attempt blocked. Miralem Pjanic (Juventus) right footed shot from outside the box is blocked. Assisted by Cristiano Ronaldo.
Foul by Leonardo Bonucci (Juventus).
Arkadiusz Milik (Napoli) wins a free kick in the defensive half.
Attempt saved. José Callejón (Napoli) left footed shot from the centre of the box is saved in the centre of the goal. Assisted by Arkadiusz Milik.
Foul by Rodrigo Bentancur (Juventus).
Allan (Napoli) wins a free kick in the defensive half.
Attempt blocked. José Callejón (Napoli) right footed shot from outside the box is blocked.
Substitution, Napoli. Fabián Ruiz replaces Marek Hamsik.
João Cancelo (Juventus) is shown the yellow card for a bad foul.
Foul by João Cancelo (Juventus).
Kalidou Koulibaly (Napoli) wins a free kick in the attacking half.
Foul by Mario Mandzukic (Juventus).
Kevin Malcuit (Napoli) wins a free kick in the defensive half.