Massimiliano Allegri's runaway leaders extended their unbeaten Serie A run to 24 matches and moved 14 points clear of closest challengers Napoli, who play Torino at home on Sunday.

Frosinone, who had won two of their previous three matches, remain second from bottom, two points from safety.

Juve were given an early scare when Frosinone striker Daniel Ciofani's header forced Wojciech Szczesny into a sprawling low save.

But the Italian champions responded immediately through Dybala, who rifled the ball into visiting goalkeeper Marco Sportiello's top left-hand corner after taking a short pass from Ronaldo on the edge of the penalty area.

It was Dybala's first league goal since November and only his third in Serie A this season.

Sportiello kept out a long-range drive from Ronaldo, who then headed wide, and Mario Mandzukic's header was also saved.

But Juve struck an inevitable second in the 17th minute. Mandzukic's header from Dybala's corner was parried by Sportiello and Bonucci forced home the rebound from a yard out with a raised boot.

The home side, fully in control, rarely shifted into anything near top gear, but Frosinone served a warning in the 32nd minute when Ciofani headed wide after they had strung together their best move of the half.

Frosinone went even closer in first-half stoppage time when Camillo Ciano's sweetly-struck free-kick curled narrowly off target.

Bartosz Salamon deflected Dybala's fine cross at the start of the second period to deny the lurking Ronaldo, who then headed a corner inches over.

Juve sliced through Frosinone's defence to notch their third in the 63rd minute.

Dybala and Mandzukic combined down the right and Ronaldo brilliantly converted the latter's low cross first time from inside the area.

The Portuguese, who has scored five goals in his last four league games, was immediately replaced by Federico Bernardeschi as Allegri clearly had one eye on next Wednesday's Champions League tie in Spain against Atletico Madrid.

Frosinone battled gamely on, but Ciano wasted a rare chance when his free-kick hit the wall.

Can's header and Bernardeschi's fierce drive were both saved by Sportiello in the closing stages as Juve cantered to another win.

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