Napoli suffered a third straight Serie A defeat after a 2-0 loss at the hands of Fiorentina on Saturday night.
Federico Chiesa got the scoring underway in the 26th minute, before Duan Vlahovic sealed the victory on 74 minutes.
As a result, Napoli have slipped to 13th on the table while Fiorentina moved up to 12.
Lazio were in a rampant mood after thrashing Sampdoria 5-1 at Stadio Olimpico on Saturday afternoon.
The hosts raced into a three-goal lead in the first half thanks to a brace from Ciro Immobile and a solitary strike from Felipe Caicedo.
Bastos bagged Lazio's fourh before Immboli completed his hat-trick in the 65th minute. Karol Linetty bagged Sampdoria's consolation.
Sassuolo rallied from behind to defeat Torino at the Mapei Stadium on Saturday night.
The visitors went ahead after 20 minutes courtesy of own goal from Manuel Locatelli.
Jeremie Boga restored parity for Sassuolo in the 61st minute before Domenico Berardi sealed the win with his ninth goal of the season after 73 minutes.