Juventus recovered from Dries Mertens' early goal to ease past Napoli, who had Mario Rui dismissed just before the hour mark.
Mario Mandzukic scored twice as Juventus secured an important 3-1 victory over 10-man Serie A title rivals Napoli at the Allianz Stadium.
A seventh straight win for Massimiliano Allegri's side means they are now six points clear of second-place Napoli – a lead that could be reduced to five on Sunday should Sassuolo continue their fine start to the season by beating AC Milan.
Napoli took an early lead through Dries Mertens, before Cristiano Ronaldo and Mandzukic combined to equalise.