Champions Juventus continued their resurgence by beating Hellas Verona 3-0 at home for an eighth successive Serie A victory as Inter Milan remained top after winning 1-0 at Empoli.
Juventus, who took one point from their opening three matches and were 11 behind the leaders on Oct. 31, are now third on 36 points after goals from Paulo Dybala, Leonardo Bonucci and Simone Zaza earned them a comfortable win.
Chasing a fifth consecutive Italian title, Juve are three points behind Inter, who retain top spot after seeing off Empoli, with captain Mauro Icardi scoring the only goal of the game.
Fiorentina were helped to a 3-1 victory at Palermo by two goals from Josip Ilicic, and are in second on 38 points, three ahead of Napoli, who would overtake them with a win at home against Torino later on Wednesday.
AS Roma's stuttering season continued when they twice let a lead slip to draw 3-3 at Chievo, leaving them fifth on 33 points and increasing the pressure on coach Rudi Garcia.
Roma, who took the lead when teenage striker Sadiq Umar scored for the second game running in his first league start, have won one of their last nine games in all competitions and recently exited the Italian Cup to second-tier Spezia.
Bologna's Emanuele Giaccherini scored in the 82nd minute to secure a surprise 1-0 win at AC Milan, while Frosinone and Sassuolo drew 2-2, Udinese defeated Atalanta 2-1 and Lazio's clash with Carpi finished goalless.
With Serie A returning from its winter break, Juventus continued where they left off in December.
The Turin side took the lead when Dybala scored his ninth league goal of the season, curling a fine free kick into the corner of the net in the eighth minute after Samuel Souprayen had brought down Stephan Lichtsteiner.
Dybala was decisive again when his superb free kick was met emphatically by Bonucci in the 45th minute and Paul Pogba set up Zaza with eight minutes remaining to leave winless Verona bottom on eight points.
"We're back in the Scudetto (title) race and that's important," Juventus coach Massimiliano Allegri told Mediaset Premium.
"We've won eight in a row and we've got to put points in the bag now. The key is to reach the last six rounds in a good position."
Inter suffered a surprise home defeat to Lazio in their final game of 2015, but returned to winning ways when captain Icardi found the net in first-half stoppage time against Empoli, turning home a fine cross from Ivan Perisic for his eighth league goal of the season.
Roberto Mancini's side have the best defensive record in the division, but were troubled on occasion during the second half, with Empoli aggrieved not to have been awarded a penalty when Manuel Pucciarelli was impeded in the box.
Roma's Umar had found the net as they ended a seven-game winless run against Genoa before the winter break and struck again in the seventh minute against Chievo.
Alessandro Florenzi added a second 30 minutes later, but Chievo drew level with goals from Alberto Paloschi and Dario Dainelli.
Roma's Iago Falque made it 3-2 with a low strike in the 71st minute, but the home side equalised again when goalline technology showed that Simone Pepe's effort had crossed the line.
Fiorentina's Ilicic opened the scoring against Palermo in the 13th minute by knocking the ball between Edoardo Goldaniga's legs and finishing beneath Stefano Sorrentino.
The midfielder added a sublime second in the 42nd minute, making space on the edge of the box before slamming home a curling effort.
Alberto Gilardino halved the deficit in the 77th minute, but Jakub Blaszczykowski added a late third.