Juventus underlined their status as title favourites with a 4-1 hammering of Roma in Turin on Saturday, which made it 45 games unbeaten for the Old Lady.
Napoli, however, maintained their early season title charge by dominating Sampdoria in a thrilling match decided by a disputed second-half penalty.
As Marek Hamsik dribbled his way into the area, the Slovakian midfielder was tripped by defender Daniele Gastaldello on the edge of the area.
The referee pointed to the spot, Gastaldello was sent off and Uruguayan striker Cavani, who scored a hat-trick in a midweek win over Lazio, stepped up to put Napoli into the lead and take his tally to five goals in six games.
Along with Juventus, Napoli are now the only unbeaten side in Serie A, with Sampdoria suffering their first defeat of what has so far been a promising campaign.
While Sunday's early fixture between Udinese and Genoa finished in a scoreless draw, no fewer than 22 goals were scored in six afternoon games.
Diminutive striker Fabrizio Miccoli was the star of the show in Sicily as Palermo hammered Chievo 4-1 at home to claim their first win of the season in emphatic style.
Bologna's second win of the campaign was a 4-0 thrashing of Catania, while Torino moved up to sixth place with a 5-1 win at hapless Atalanta.
Lazio got over their midweek setback against Napoli with a 2-1 home win over struggling Siena, while Cagliari suffered a 2-1 home defeat by Pescara to remain the only team without a win in the league.