Carlo Ancelotti bemoaned Napoli's sloppy mistakes after his side fell to a 3-1 defeat to Serie A title rivals Juventus on Saturday.
Partenopei took the lead through Dries Mertens after seizing on a loose Leonardo Bonucci pass but Mario Mandzukic's brace and a later Bonucci effort ensured the Italian champions ran out comfortable winners following Mario Rui's red card.
Speaking after the game, Ancelotti hinted at his frustration with the referee but admitted Napoli didn't help themselves with some bad mistakes.
He said, as quoted by Calciomercato: "I think that the referee made a few funny decisions. Mario Rui was sent off but the referee had to think about it for a long time.
"We started the game very well and even took the lead but we then fell asleep at times and we made some sluggish mistakes.
"I think we did pretty well overall but we still have to improve a lot. Improvements? Well I think we have to be more consistent and we need to have a stronger character.
"Ten men? I think we did pretty well down a man considering we were playing in Turin. Juve fans? Well their chants were not a surprise. I console myself with the 2003 UCL Champions league with AC Milan. We have to keep on fighting hard and keep on hoping."
Next up for Napoli is a Champions League clash with Liverpool in what is a massive game for Ancelotti's side after failing to win their opening group game at Red Star Belgrade.