Inter Milan went back top of Serie A with the easiest of 4-0 wins over Frosinone on Sunday evening.
Jonathan Biabiany put Inter ahead in the first half and that allowed Nerazzurri to run riot after the break, scoring three goals.
Mauro Icardi, Jeison Murillo and Marcelo Brozovic did the damage to earn a fourth straight win and knock Napoli down to second.
Napoli had gone to the summit after they maintained their impressive form with a 2-0 win at Verona.
Maurizio Sarri's men were made to work hard, though, as they had to rely on quickfire second-half goals from Lorenzo Insigne and Gonzalo Higuain.
Once Napoli got in front there was little hope for Verona and the visitors saw out a fifth successive league match without conceding a goal and a 12th game unbeaten overall.
Substitute Nikola Kalinic scored twice in the second half as Fiorentina came from 2-0 down to earn a point against Tuscan rivals Empoli.
Goals from Marko Livaja and Marcel Buchel gave Empoli a first-half lead in Florence before Kalinic came on after the restart to spark the Viola's attack and secure a 2-2 draw.
Lazio substitute Antonio Candreva's second-half penalty denied new Palermo coach Davide Ballardini victory in Rome as it ended 1-1 after Edoardo Goldaniga had put the visitors ahead.
Udinese secured a much needed 1-0 victory against Sampdoria, with Emmanuel Agyemang-Badu scoring the only goal of the game in Vincenzo Montella's first game in charge of Samp.
Elsewhere, Torino beat Atalanta 1-0 thanks to Cesare Bovo's goal, Chievo halted a seven-match winless run with a 2-0 triumph at strugglers Carpi and Leonardo Pavoletti struck the winner at the death as Genoa defeated Sassuolo 2-1.