Napoli beat Sampdoria 2-0 ahead of their Champions League meeting with Liverpool on Tuesday.
Carlo Ancelotti's side host the European champions in their opening Group E fixture next week and, like the Reds, go into that game on the back of a domestic victory.
Dries Mertens scored in either half to defeat Sampdoria at Stadio San Paolo on Saturday evening.
Speaking post-match, Ancelotti said: "It was a good display and we deserved the win.
"It was important to impose our game and keep a clean sheet as well. In the first half, we made a few mistakes bringing the ball out which allowed them to break.