Juventus enjoyed a brief spell at the top of Serie A thanks to their 4-0 win at Chievo but were quickly replaced by Napoli, who racked up a 5-1 victory against Empoli.
The sides went into Sunday's action separated by two points and both appear certain to go head-to-head for the Scudetto as they secured convincing wins before the Milan derby rounds off the weekend's action.
Juve were in action first and were set on their way to a 12th consecutive Serie A win by Alvaro Morata's first-half brace as Chievo struggled for momentum without Alberto Paloschi, following his move to Swansea City.
Alex Sandro and Paul Pogba made a comfortable win easier with quick-fire strikes after the hour as the champions' mid-season recovery now leaves them just one win shy of matching a club-record run.
Nevertheless, Juve remain off the pace as Napoli matched their nearest challengers.
Empoli midfielder Leandro Paredes opened the scoring and gave those in Turin hope of a slip-up but Gonzalo Higuain's 22nd league goal of the season levelled matters just five minutes later.
Lorenzo Insigne, Michele Camporese's own-goal and a Jose Callejon brace returned Maurizio Sarri's men to top spot in style as they reached the 50-goal mark in Serie A.
Paulo Sousa was sent to the stands late on for kicking a ball that remained in play as Fiorentina were held 0-0 by Genoa while Udinese and Lazio had a man each dismissed in their goalless stalemate.
Rock-bottom Verona remain winless as they failed to find a way past Torino in their 0-0 draw at the Stadio Olimpico although there were goals aplenty at the Stadio Renato Dall'Ara as Bologna edged a five-goal thriller against Sampdoria 3-2, Mattia Destro sealing the points from the spot after Ricky Alvarez handled the Italian's goalbound header three minutes from time.