Napoli coach Maurizio Sarri wants his players to improve the mental side of the game ahead of tomorrow's clash at home against Sampdoria.
Sarri was impressed by the Blucerchiati's performance away at Carpi last week as they eased past Fabrizio Castori's men by 5-2.
And he warned his players to be extremely careful in defence against the quick Sampdoria players.
"We have to show character [against Sampdoria]," Sarri told reporters on Saturday afternoon.
"I didn't see fitness issues [last week] against Sassuolo, I believe the key will be to be aggressive and to put the game to bed when we have a chance to do so.
"We have to improve mentally because even if we're not 100% in respect to fitness level, we can still show that we are quality.
"It's unacceptable that we run out of steam after only 20 minutes.
"Sampdoria are in a very good physical condition, I saw their first half against Carpi and they were impressive. They have fast players in attack like Eder and Muriel so we have to be careful."