Edinson Cavani scored his eighth goal in 11 Serie A matches as Napoli stayed on the heels of champions Juventus with a 1-0 win at Sampdoria.
Napoli have an identical record to Juventus with five wins, a draw and 16 points from their opening six league matches of the season, but Antonio Conte's side are two goals better off on goal difference boosted by their 4-1 win over Roma on Saturday night.
Cavani settled a tight match in favour of his side when he planted a penalty into the corner of the net on 67 minute after Marek Hamsik had been felled by Daniele Gastaldello in the Sampdoria box.
Gastaldello was sent off for collecting a second yellow card and was probably not back in his dressing room when Cavani stuck the ball to the left of Sergio Romero with the home goalkeeper given no chance.
Sampdoria tasted defeat for the first time in Serie A this term, but remain fourth in the standings and will be encouraged by the spirit they unearthed against a Napoli side who will surely have ambitions of challenging Juventus for the title this term.
The home went into the match hamstrung by a length injury list that denied them Nicola Pozzi, Andrea Poli, Fernando Tissone and Juan Antonio. With Maxi Lopez and Enzo Maresca suspended, Roberto Soriano started the match.
The home side created the first chance of the match when Gianni Munari just failed to connect with the ball in the box from a corner after Nenad Krsticic had helped the ball on.
Gastaldello nodded just over the bar on 23 minutes from an Pedro Mba Obiang free-kick before the game became bogged down in a real dogfight in midfield with bookings - six men collected yellow cards - rather than clear-cut chances becoming the order of the day.
It all got too much for the Napoli coach Walter Mazzarri, who was sent to the stands for complaining about Obiang's tackle on Gokhan Inler seconds before the break that earned the Napoli player a deserved booking.
In hindsight, Mazzarri might feel a bit embarrassed about his conduct considering Napoli emerged unscathed from the afternoon.
Elsewhere, Fabrizio Miccoli scored a brilliant hat-trick, including an astonishing volley from around 40 metres, as Palermo hammered Chievo 4-1 to claim their first win of the season.
Miccoli opened his account by curling a free kick around the wall in the 13th minute.
Marco Rigone levelled in the 28th minute but Miccoli put Palermo back in front with an individual goal just before the hour and completed the scoring with a volley from near the halfway line which sneaked under the crossbar.
Luigi Giorgi also scored to ease the pressure on Palermo coach Gian Piero Gasperini, whose predecessor Giuseppe Sannino was sacked after only three games at Italy's most volatile club.
The only sour note for Palermo was a red card for Franco Brienza in the 62nd minute.
Cagliari, playing a home match in front of supporters for the first time this season, lost 2-1 to Pescara to remain winless.
Around 5,000 fans were allowed to watch Cagliari's game as the Is Arenas stadium, where the Sardinian club has moved this season, was partially opened.
Cagliari's first game was played behind closed doors while their match with AS Roma last Sunday was called off by local authorities after club president Massimo Cellino defied a municipal order not to allow fans to attend.
Roma were awarded a 3-0 forfeit win.
There was little joy, for Cagliari, however as Christian Terlizzi and Vladimir Weiss scored in the second half to put the visitors 2-0 ahead before Mauricio Pinilla pulled one back from a penalty.
Lazio beat Siena 2-1 thanks to first-half goals from Ederson, the Brazilian's first since joining from Olympique Lyon, and Cristian Ledesma, who converted a penalty.
Torino scored four goals in a quarter-of-an-hour during the second half to win 5-1 at Atalanta, who hit the woodwork twice and took the lead as they dominated the first half, and Bologna thrashed Catania 4-0.
Udinese and Genoa played out a 0-0 draw.