Victor Osimhen has scored twice and Hirving Lozano helped set up three of the goals as Napoli impressed in a 4-0 win at Sampdoria to extend their perfect start to the Serie A season with a fifth straight win.
Chasing their first Italian league title since Diego Maradona led the Partenopei to their only championships in 1987 and 1990, Napoli returned to the top of the standings on Thursday, moving two points ahead of defending champions Inter Milan and AC Milan.
Sampdoria held Inter to a draw this month and were seen as a potential obstacle for Napoli but Luciano Spalletti's team controlled from the start.
The Nigerian Osimhen started things off when he pushed in a cross from Lorenzo Insigne at the far post, having already come close minutes earlier.
Passes from Lozano and Insigne set up Napoli's second for Fabian Ruiz from the edge of the 18-yard box.
Osimhen then needed only one touch to redirect a Lozano cross from the centre of the area.
Lozano then had an assist of his own when Piotr Zielinski pounded in another for Napoli, on a play started by the newly acquired midfielder Andre Anguissa, who's on loan from English side Fulham.
Elesewhere, new Roma striker Tammy Abraham impressed the local fans by singing along to the team's anthem before the match against Udinese and then scored the first-half goal that gave the Giallorossi a 1-0 win.
It was Abraham's third since joining from European champions Chelsea in a 40 million euros ($A64 million) transfer.
Fourth-placed Roma moved one point behind the Milan clubs with their seventh win in eight matches across all competitions under Mourinho.
Ciro Immobile converted a penalty in stoppage time to earn Lazio a 1-1 draw at Torino, after a header from Mark Pjaca had put Torino ahead in the 76th.
Australian Associated Press