Napoli coach Maurizio Sarri has admitted his side were too complacent after their 18-match unbeaten run in all competitions came to a halt with a defeat at Bologna.
Sarri's side missed the chance to go back to the top of Serie A as they lost 3-2 on Sunday, with Gonzalo Higuain's late double proving nothing more than a consolation.
Despite a fast start from the visitors, Mattia Destro's double either side of Luca Rossettini's header had put Bologna into a commanding lead, and Sarri claims that Napoli must focus on re-finding their form at the back.
"We ran into every pitfall that we could have had in this game. We'd talked about all the potential pitfalls, the risk of arriving for this game with less concentration than needed," he told Sky Sport Italia.
"We had come off a big game against Inter and were simply unable to recharge the batteries quickly enough. Perhaps there was a little bit of complacency too.
"We must focus on the details, because the team is allowing far more than it used to in previous matches.
"We had a long spell with great concentration and now we are having a dip. We must learn the principle element is concentration in defence.
"What changes after this defeat? It changes nothing for us. In fact, losing a game could be useful to rediscover the right attitude for the next one."
