Juventus pulled nine points clear at the top of the Serie A table by punishing traditional rivals Inter Milan 3-1 in the second Derby d'Italia of the season.
With second-placed Roma left in limbo following the abandonment of their rain-soaked meeting with Parma earlier on Sunday, Juve knew victory over their old foes Inter would give them a significant advantage in the title race.
It did not take Stephan Lichtsteiner long to strike the first blow in the 3-1 win, courtesy of an exquisite assist from Andrea Pirlo, and Giorgio Chiellini made it a real uphill battle for struggling Inter with a goal right after half-time.
When Arturo Vidal added a third, Juve could start celebrating their fifth derby victory from seven recent encounters, with a late consolation goal from Inter defender Rolando doing little to rattle the reigning champions' nerves.
Bergamo has been an inhospitable venue for Napoli over recent years and a brace from German Denis preceded Maxi Moralez's late goal to condemn the southerners to a fifth defeat from their last eight league games here.
More pressing than the fact Jose Reina, Gokhan Inler and Federico Fernandez each made glaring errors to facilitate Atalanta's goals is the fact that Napoli missed an opportunity to catch up with league leaders Juventus and second-placed Roma, who are eight and six points better off respectively.
Roma might have extended that advantage had their meeting with Parma not been abandoned after only eight minutes of rain-affected play.
There was doubt the league game at Rome's Stadio Olimpico would go ahead at all on Sunday due to incessant heavy rain affecting the Italian capital and kick-off was delayed for several minutes.
Only eight minutes of play took place before referee Andrea De Marco decided to suspend the game for 30 minutes, pending a pitch inspection, but the match was soon officially abandoned following the interruption.
The 18-year-old caused Chievo's defenders a whole host of problems before getting his name on the scoresheet in the second half to seal all three points after Antonio Candreva's early opener.
Alberto Malesani failed to make a winning start as Sassuolo coach as Hellas Verona claimed a 2-1 victory at the Stadio Citta del Tricolore.
Malesani's first assignment since replacing Eusebio Di Francesco in the Sassuolo dugout was a game against his hometown club Verona, who also won automatic promotion from Serie B last season.
Thomas Manfredini made life difficult for the relegation-threatened Neroverde with an own-goal in the 50th minute before veteran striker Luca Toni doubled Verona's lead four minutes from full-time.
Antonio Floro Flores scored a late consolation for Malesani's men but they remain a point from safety ahead of next weekend's daunting trip to Inter Milan.
Serie A strugglers Catania and Livorno shared six goals in a survival thriller at the Stadio Massimino.
Livorno took the lead three times, but were pegged back each time by a courageous Catania, who almost snatched victory in stoppage time of the 3-3 draw.
Innocent Emeghara scored two for Livorno and earned a penalty, which was converted by Paulinho.
Gonzalo Bergessio, Pablo Barrientos and Sergio Almiron replied for the hosts, earning them a point which does not help either side much in their respective battles against the drop.
On Saturday night, AC Milan dropped their first points under Clarence Seedorf as high-flying Torino came away from the San Siro with a 1-1 draw.
Ciro Immobile gave the visitors the lead in the 17th minute, but an Adil Rami strike early in the second half earned the Rossoneri a point.
Milan put Torino under pressure for much of the second half, but failed to find a winning goal, leaving Seedorf with only a point after two wins in his first two Serie A games in charge.
Udinese ended a run of four successive Serie A defeats with a 2-0 win at Bologna that will ease their relegation fears.
Udinese have finished fifth, third and fourth in the last three seasons but they have recently found themselves battling at the wrong end of the table after failing to take point from their first four matches of 2014.
However, they brought that miserable run to a close on Saturday after goals from Antonio Di Natale and Nicolas Lopez earned them a three-point haul from their trip to fellow strugglers Bologna.
Mauricio Pinilla earned Cagliari their first Serie A victory in seven attempts as his first-half penalty settled a 1-0 home victory over an uninspiring Fiorentina side at the Stadio Sant'Elia.
It was difficult to tell which club was challenging for a top-three spot and which one was battling to avoid a relegation battle as Cagliari tormented Fiorentina goalkeeper Neto for over an hour in Sardinia.
Pinilla scored a penalty shortly before half-time to lift Cagliari into 13th place while Vincenzo Montella's Fiorentina could now see Inter Milan close to within five points of taking fourth place with victory at Juventus on Sunday.