Gattuso, who will be coaching in the competition for the first time in Tuesday’s match, replaced Carlo Ancelotti in December with the team in disarray after the club fined the players for refusing to take part in a training camp.
Rules, respect and coherence have helped dig Napoli out of a hole, their coach Gennaro Gattuso said on Monday, as they prepared to host Barcelona in their Champions League round of 16 first leg.
Gattuso, who will be coaching in the competition for the first time in Tuesday's match, replaced Carlo Ancelotti in December with the team in disarray after the club fined the players for refusing to take part in a training camp.
His initial attempts to remedy the situation only made things worse as they lost four of their first six matches under his leadership, dropping to 13th in Serie A.
They then reached a low point with a home defeat against Fiorentina which Gattuso described as embarrassing.
The 42-year-old, renowned as being one of the most fiercely competitive players of his generation, is not one to give up easily, however, and took them away to a training camp so they could discuss things "face to face".
Whatever was said behind closed doors seemed to do the trick as Napoli have won six of their subsequent seven games in all competitions, including cup wins over Inter Milan and Lazio as well as a league win over Serie A leaders Juventus.
"You win over the squad by working hard every day, with rules, respect and coherence," Gattuso told reporters.
"When you are managing 25 footballers and other people who you are in contact with every day, it is about finding the right words for everyone, telling them the truth. You have to say the bad things as well."
Gattuso was also grateful to Ancelotti, who was sacked immediately after Napoli beat Genk to reach the last 16. "I have to thank the team and Ancelotti because I haven't done anything," he said.
Napoli have never gone beyond the last-16, which they have reached for the third time, and it remains a tall order for them to overcome Lionel Messi's Barcelona.
"We have to play without fear," said Gattuso. "I want to see a team that is prepared to suffer."
"Messi is incredible, he can do things that you only see on Playstation, but we have to try and stop him," added the former midfielder, who faced Barcelona six times in his playing days.
"We used to say at the end of the match that we were playing another sport because they wouldn't let you touch the ball," he said. "They destroyed you mentally."