Paolo Di Canio has admitted poison seeped into the veins of his players in the run-up to their 6-1 defeat at Aston Villa on Monday night.
The heavy loss has pushed Sunderland back into the Premier League relegation fight and Di Canio has blamed the celebrations that followed successive victories against Newcastle and Everton.
He has also called on his players to play with more of an edge as they bid to find the points to keep Sunderland out of the Championship.
"We felt safe and after Everton we relaxed," said Di Canio. "After the Newcastle result, it was poison. It's not acceptable. I can understand it, but it's not acceptable. It happened with a group of genuine players, they didn't do it because they wanted to or because they're bad professionals.
"We have to accept the process to extend the motivation to always want more. You can't change the mentality in two or three weeks. There was a three-day party [after Newcastle], I couldn't go 300 yards to cut my hair. There's a tradition in Naples they all come out. You can't go out because a butcher comes out with meat saying, 'It's for you, for your family'. I couldn't go into town. I went 300 yards, 20 people. This is four days after what happened they pass word to each other.
"Many girls came and hugged me and I was wondering what was going on. I couldn't imagine the passion. I can imagine players around town. They feel big. We have to make sure for the future we don't get poisoned.
"They are very genuine, but very shy. Before what happened to Stéphane Sessègnon [getting sent off against Villa], this team had not had one red card. Now, I don't want to see my players getting red cards, but even in terms of yellow cards, this isn't a team that has suffered much in that respect. Reading and QPR are relegated, but they have two of the best records in the league in terms of getting yellow cards. They have had very few.
"I'm not saying you have to get yellow cards, but maybe we are too nice. I'm not saying we have to have the devil in us because people will say, 'Di Canio wants a killer in his team'. But while this is a very genuine group, we are sometimes too clean. We need to have a bit more of an edge."