Ronaldo, signed for £99.2m in the summer, netted his 17th goal of the season with a thumping spot-kick.

Juve looked to be heading for their first defeat since last April when Emre Can miscued into his own goal.

But substitute Joao Cancelo struck from close range to level the contest before Ronaldo kept his cool for victory.

Massimiliano Allegri's side capitalised on Napoli's goalless draw against AC Milan on Saturday and are now firm favourites to claim the title for the eighth straight season.

Juventus will be aiming to progress into the semi-finals of the Coppa Italia when they face Atalanta in their next game on Wednesday.