Lorenzo Insigne's late winner gave Napoli a deserved 1-0 Champions League victory over Liverpool on Wednesday that saw the Italians move to the top of Group C.
The Serie A side, who drew 0-0 away to Red Star Belgrade in their opening game, controlled large spells of the match at the Stadio San Paolo, but failed to break down last season's runners-up until the 90th minute.
Napoli produced the better chances in a tightly-contested first half, but a muted Liverpool team failed to muster a shot on goal until Mohamed Salah's tame effort in the 67th minute flew harmlessly wide.
The hosts increased the pressure as the minutes ticked down, with substitute Dries Mertens volleying against the crossbar 10 minutes from fulltime, but Insigne secured the points when he tapped in from a Jose Callejon cross.
"It's wonderful to win like this, but we had a great performance as a team and wanted the result at all costs," Insigne told Sky Italia.
"Now we'll enjoy this victory for a little bit...
"We know it's a difficult group, we always did, but we want to make our mark in every game and put any opponent under pressure."
Napoli top the group with four points, with Paris Saint-Germain and Liverpool on three and Red Star Belgrade on one.