Rafa Benitez was left ruing Napoli's costly mistakes and constant profligacy following Sunday's 3-0 defeat at Atalanta.
The Partenopei were the inferior side at the Stadio Atleti Azzurri d'Italia, with German Denis' double and Maxi Moralez's strike ensuring an embarrassing defeat for Serie A' third-placed side.
Benitez felt that his team started well but were made to pay for error after error in their own half, insisting Napoli must learn to net against teams which play compact football.
"We had to play with sharpness and quality to win," he told Sky Sport Italia. "We had three or four promising counterattacks in the first 45 minutes, then started the second half with a mistake.
"We had a chance, then a mistake, then another chance, then another mistake. Of course it becomes nigh-on impossible to get back into a game after making so many mistakes.
"I don’t think these errors have happened before, but they completely changed the game. If we don’t take our chances and the other team does, then of course we are going to lose. There was also a penalty appeal for Dries Mertens.
"It is difficult to find space against teams like Chievo, Bologna and Atalanta, but we must learn to score more goals."
Napoli will look to bounce back in Wednesday's Coppa Italia semi-final first leg at Roma, who only played 10 minutes of football on Sunday after a waterlogged pitch suspended their clash with Parma.