Gennaro Gattuso has called for a mentality change at Napoli after his side exited the Champions League with a 4-2 aggregate defeat to Barcelona.
First-half goals from Clement Lenglet, Lionel Messi and Luis Suarez ultimately proved enough for Barca to win 3-1 in the second leg of the last-16 tie on Saturday, with Lorenzo Insigne's penalty proving a mere consolation for the visitors at Camp Nou.
Napoli had a total of 18 shots to Barca's seven, but lacked the cutting edge to forge a comeback.
But with a Europa League place next season secured thanks to their Coppa Italia triumph, Gattuso feels Napoli must now focus on improving their mentality if they are to become a title-challenging side.
"There are many regrets, because we had a blackout for half an hour, conceded three ridiculous goals and made some very serious errors during that period," Gattuso told Sky Italia.
"I saw a team that also put Barcelona under huge pressure. We should've scored two goals early, yet we conceded instead. It angers me to concede a goal from a set play. It drives me crazy.
"I always say, we have some strong and talented players, but need to really move forward in terms of mentality, because it's not good enough.
"If you look at the statistics, it was dominated by Napoli. We had double their shots on goal, had more possession, we broke through their defence very easily.
"I am not trying to cause controversy, I am disappointed because I saw we could really hurt them. I get the feeling we were up against a Barcelona side that was not in good shape and we handed it to them.
"With a little more determination and a stronger mentality, we could've really done damage here."
Gattuso did, however, concede Barca's longer break since the end of their LaLiga campaign may have played a part.
"You could see Barcelona were really struggling in the second half. I think the fact they had 19 days without playing made a big difference," he said.
"It annoys me that even with all that, we still couldn't make the most of it. When you give them an inch, obviously they're going to take those chances and we didn't. It hurts."