Juventus extended their Serie A lead to six points after a 1-0 defeat of Inter Milan in the Derby d'Italia at the Juventus Stadium on Sunday.
Juan Cuadrado's stunning long-range strike just before the break proved the only goal the hosts would need so sink their arch rivals in a tense affair which produced seven yellow cards on the day.
Juventus twice hit the post in the first half as they looked most likely to break through, and were rewarded for their persistence by the Colombia international on 45 minutes.
From a corner, the Juventus winger left Samir Handanovic no chance, drilling a powerfully hit shot into the top-right corner from 22 yards out for his first league goal of the season.
The victory leaves the five-time defending league champions with 54 points from 22 matches, while enjoying a game in hand over second-placed Napoli.
Injury-hit AC Milan were plunged further into crisis by a surprise 1-0 defeat at home to Sampdoria in Serie A on Sunday.
Luis Muriel's 69th-minute penalty was enough to consign Milan to their fourth successive defeat in all competitions.
Milan were third in December but one point from their past four league matches has seen them slip to eighth, 10 points behind the Champions League places.
Meanwhile, Marco Parolo scored four times as Lazio got back on track following two successive league defeats, although they had to withstand a Pescara comeback in a match that ended 6-2.
Two Parolo headers had given Lazio a seemingly comfortable lead inside 14 minutes. But Pescara levelled the match shortly before half-time.
First Ahmad Benali rushed in to tap a rebound into the bottom left corner after Federico Marchetti could only parry Grigoris Kastanos' effort.
Gaston Brugman volleyed the equaliser into the far corner four minutes before half-time, after Pescara had also seen Gianluca Caprari's penalty saved by Marchetti -- awarded for a foul by Wesley Hoedt on Francesco Zampano.
Parolo completed his hat trick with another header four minutes after the break and Keita Balde Diao restored Lazio's two-goal advantage shortly before the hour.
Ciro Immobile scored Lazio's fifth with a half volley at the back post from a corner. The Italy forward did not celebrate as he spent a season on loan at Pescara, helping them to the Serie B title in 2012 and finishing as the second division's top scorer.
Parolo, who only scored three goals all last season, netted his fourth of the game in the 77th minute with a low volley from Senad Lulic's cross.
Andrea Belotti netted his 15th league goal of the season but his Torino side could only draw 1-1 at Empoli, in a match affected by heavy rain.
Empoli levelled on the stroke of half-time after Arlind Ajeti's backpass was stopped by a puddle, allowing Manuel Pucciarelli to get there before Joe Hart, take it past the England goalkeeper and put it into an empty net.
Iago Falque saw a penalty saved by Empoli goalkeeper Lukasz Skorupski.
Ilija Nestorovski struck in the first half to help Palermo win a relegation battle over Crotone, who had Lorenzo Crisetig sent off in the second half.
Papu Gomez scored twice as Atalanta beat Cagliari 2-0 to move level with Inter.
Elsewhere, Chievo Verona drew 0-0 with Udinese and Sassuolo won 1-0 at Genoa thanks to Lorenzo Pellegrini's early strike.