Juventus hung on with Mario Mandzukic's first-half header to beat Roma 1-0 in Serie A on Saturday (Dec 22) and clinch the unofficial winter title with two matches remaining before the halfway point.
Juventus, seemingly unstoppable en route to an eighth successive Serie A title, have an eight-point lead over second-placed Napoli, who beat Spal 1-0.
Roma goalkeeper Robin Olsen atoned for last week's errors against Genoa with fine saves but could do nothing 10 minutes from half-time when Mandzukic rose high at the far post to head in Mattia De Sciglio's cross from the right.
Olsen kept Juventus at the bay in the second half, including denying Cristiano Ronaldo twice in quick succession. Ronaldo has not scored from open play in four consecutive matches.
He thought he set up Juve's second with some good play on the right side of the penalty area before passing for Douglas Costa to poke home, but the goal was ruled out for a Blaise Matuidi foul on Nicolo Zaniolo.
Third-placed Inter are 16 points behind Juventus after only drawing at bottom club Chievo Verona 1-1.
Sergio Pellissier netted a stoppage-time equaliser to cancel out Ivan Perisic's first goal for Inter in nearly three months. Lazio ended a seven-match winless run to leapfrog AC Milan into fourth spot and the final Champions League berth.
Sergej Milinkovic-Savic ended his three-month goal drought to set Lazio on their way to a 3-1 win over Cagliari.