Carlo Ancelotti insisted that there was no sense of "euphoria" after beating Champions League holders Liverpool 2-0 in the opening match of the campaign.
Dries Mertens and Fernando Llorente scored late as Liverpool fell in their Group E game in the San Paolo Stadium on Tuesday night.
"Euphoria at what? We won the first match, it was a good test and we come out of this match aware that this team can do well," said Ancelotti.
"It was just one victory, but yes it has given us confidence, being able to match Liverpool is impressive as for me they are the best team in Europe at the moment.
"It's proven that this team can perform very well, dig in and make sacrifices."
Ancelotti has started his second season at Napoli with the Italians going out in the group stage last year after losing to Liverpool at Anfield, having beaten Klopp's side beforehand in Naples.
"We brought in important players who improved the quality of the squad and have different characteristics to what we had before," said the 60-year-old, whose side are fourth in Serie A.
The three-time Champions League winning-coach — twice with AC Milan and once with Real Madrid — said his focus was just on getting out of the group stage.
"I thank (Liverpool coach Jurgen) Klopp for saying we can win this competition," said the Italian, "but it's a long way to go. Now we must think about progressing to the knockout stages."
Belgian Mertens added: "We beat Liverpool a year ago as well, it counts for nothing if we don’t do well in the next matches."
Napoli next play Belgian side Genk on October 2, followed by a trip to Salzburg, before visiting Anfield on November 27.