Walter Mazzarri declared himself proud of his players following their win over Villarreal, but threw caution to their demanding style of play.
The Coach was talking after leading Napoli to a 2-0 win over the Spanish on Tuesday night, a result that sees them second in their Champions League Group A.
However, Mazzarri suggested the playing style could be getting the better of his men, before concluding he was delighted with their dedication.
"There were players who could not make it any longer, I would have changed five. Hamsik and Gargano always play and our game requires a constant race: if you play once a week, there would be no problem.
"We still have little experience in Europe, so we expend lots of energy: we must grow in this.
"Are we offensive? Thank goodness you do not talking about Napoli relying too much on comebacks. Even last year we often crushed opponents by 70 minutes.
"Tonight at one point we dropped too much and I'm angry: if we did not have the goals, we would have suffered.
"After the Europa League last year, I was sure that my Napoli would have had the right approach. I am proud that this team will follow me all the way."