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.
BBC reports that 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.