League leaders and reigning champions Juventus strengthened their grip on Serie A with a routine 2-0 win at Sassuolo, as title challengers Roma suffered a costly defeat at Sampdoria.
Well-taken goals from Gonzalo Higuain - his eighth in his last six league games - and Sami Khedira had the favourites in control inside the first 25 minutes at Mapei Stadium, where Eusebio Di Francesco's outclassed hosts proved ill-equipped to respond.
Juve surprisingly dropped points in a 2-1 loss at Fiorentina earlier this month, but they appear now to be firmly back on track, having claimed victory with relative ease in Modena, to follow wins over Lazio in the league and AC Milan in the Coppa Italia.
Second-placed Roma meanwhile lost 3-2 at the Luigi Ferraris on Sunday to find themselves four points back from the frontrunners.
Next weekend Juve have an opportunity to gain revenge for their 2-1 defeat at Inter in September, when the Nerazzurri make the trip to Piedmont for the second Derby d'Italia of the season. Sassuolo remain comfortably clear of the relegation zone, with a trip to immediate rivals Genoa awaiting on Sunday.
Juve shrugged off a somewhat shaky start to take the lead after nine minutes, as coach Massimiliano Allegri's attacking line-up paid dividends.
Mario Mandzukic sent Alex Sandro racing away down the left wing with a tasty back heel to complete a one-two with the full-back and Higuain did what he does best from the Brazilian's subsequent cross, getting ahead of his marker to stab home from close range in the centre of the penalty area.
Taking the lead served to settle the champions and they doubled their advantage in style in the 25th minute. Higuain closed down veteran Paolo Cannavaro and won possession in a dangerous area before cutting a pass back into the box. Paulo Dybala then fooled the Sassuolo defence with a wonderful dummy and Khedira arrived to smash the ball into the top corner of the net.
Dybala nearly made it 3-0 when he struck the post with a shot from outside the area in the 53rd minute, before Sassuolo finally tested the visitors' goalkeeper Gianluigi Buffon.
The 39-year-old produced a smart double save to deny first Matteo Politano and then his former Juve team-mate Alessandro Matri in a rare foray forward from the beleaguered home team.
That was as close as Sassuolo came to pulling a goal back and, while Juve could not find a third to put the result beyond doubt, they saw out the time remaining in comfort to earn a useful buffer at the top of the standings.
while Juve have 51 and a game in hand at lowly Crotone as Napoli trail on 45.
The Neapolitans fell behind to a sixth-minute header from Ilija Nestorovski, levelling in the 66th as goalkeeper Josip Posavec
fumbled on a Dries Mertens effort after numerous brilliant saves.
Second-last Palermo, who hired new coach Diego Lopez on Thursday, had Edoardo Goldaniga sent off in the 90th minute.