The Portuguese forward squandered a series of chances at Stadio Benito Stirpe before putting the champions on course for a fifth league win from five this term with his third goal for his new club.

Substitute Bernardeschi added a second in injury-time after Juve broke away on the counter-attack.

Lowly Frosinone, who have registered just one point following promotion, produced a dogged display, but rarely ventured forward as their search for a first goal of the campaign continued.

Second-placed Napoli remain three points adrift of Juve after Lorenzo Insigne's brace helped them to a 3-1 victory at Torino.

Italy forward Insigne lashed home the early opener for Carlo Ancelotti's side before forward Simone Verdi volleyed in a Dries Mertens cross to double the advantage with his first goal for the club.

Andrea Belotti's penalty, following a foul by Sebastiano Luperto, halved the deficit, but Insigne quickly restored the two-goal advantage by scoring a rebound after Jose Callejon's attempt came back off a post.

Roma's winless run stretched to five games in all competitions after they squandered numerous chances during the 2-0 defeat at Bologna.

Eusebio Di Francesco's team, beaten 3-0 at Real Madrid in the Champions League in midweek, fell behind nine minutes before the break when Federico Mattiello fired in from the edge of the box.

The visitors, who had 20 attempts at goal, fell further behind just before the hour mark after Federico Santander found the bottom left corner from distance.

At Stadio Olimpico, Ciro Immobile scored twice as Lazio continued their resurgence with a resounding 4-1 success over Genoa.

The hosts, who have won three in a row after losing their opening two games, were two goals ahead at the break thanks to Felipe Caicedo and Italy striker Immobile.

Serie A top scorer Krzysztof Piatek halved the deficit early in the second period with his fifth strike of the campaign, but Sergej Milinkovic-Savic restored the two-goal advantage before Immobile added his second late on.

Elsewhere, AC Milan were held to a 2-2 draw at home to Atalanta after conceding an injury-time equaliser at San Siro.

Goals from Gonzalo Higuain and Giacomo Bonaventura, either side of Alejandro Gomez's leveller, looked to have given the seven-time European champions victory until Emiliano Rigoni struck a minute into added time.

In Sunday's other game, bottom club Chievo, who have been deducted three points for false accounting, lost 2-0 at home to Udinese following second-half strikes from Rodrigo De Paul and Kevin Lasagna.