Needing to improve on their worst eight-game start to a top-flight season in 17 years, Napoli played with intent early on and punished Monza with a deserved opener.
Giovanni Di Lorenzo burst through midfield and played a perfectly weighted through ball to Rasmus Hojlund, who moved it onto his left foot and slotted into the bottom corner.
There were chances for that lead to be extended too, with Matteo Politano and Mathias Olivera both going close, but the Partenopei were not to have it all their own way in the first half.
Despite their lowly league position, Monza had become known for scoring goals in the first part of the season, and they certainly showed their capabilities.
Foe Ondoa’s powerful strike brushed the base of the post on its way out, before Serie A top scorer Gustavo Varela made Vanja Milinkovic-Savic save his next two efforts.
But there was nothing the Serbian stopper could do when Jay Robinson worked his way along the left side and lifted a cross into the six-yard box, where Varela was waiting to direct his header inside the far post and put the sides level going into half-time.
But the hosts’ momentum was quickly halted just after the break, with a mix-up on the left side of defence gifting the ball to Politano, who darted into the box and found the far corner with a deft finish.
And Napoli were ruthless from there, with a third coming when Politano’s corner was met by Rafa Marin and glanced inside the side netting of the far post.
Kevin De Bruyne then emerged from the bench to latch onto Noa Lang’s through ball and slot through the legs of Noel Tornqvist, continuing his strong run of form and wrapping up a disappointing night for the Biancorossi after showing some early promise.
Though this much-needed result reestablishes Napoli among the contenders for European qualification, they remain 11 points behind runaway leaders Inter Milan and Lazio after just nine matches. Monza couldn’t keep their home momentum going, and this is now their worst-ever start to a Serie A campaign.