Champions Juventus and Napoli pulled clear at the summit of Serie A as they continued their faultless campaigns on Wednesday as Inter Milan fell behind.

Croatia forward Mario Mandzukic scored for Juventus in a 1-0 win over old foes Fiorentina in Turin as Napoli rallied from a goal down to beat Lazio 4-1 in Rome.

Juventus and Napoli have a maximum 15 points after five games, two ahead of Inter Milan who were held 1-1 at Bologna on Tuesday.

Stefan de Vrij had given Lazio a halftime lead over Napoli, but the hosts hit back in the second half with three goals in a four-minute spree including a stunning Dries Mertens strike.

After a tense first half Mandzukic found the opening for Juventus with a diving header after 53 minutes off a Juan Cuadrado cross.