LONDON -- Mauricio Pochettino has said his Tottenham players must accept harsh criticism, revealing how Marcelo Bielsa reduced him to tears, but changed his life with some expletive-ridden home truths.
But the Spurs manager passionately rejected the suggestion that he had made a mistake by not starting Mousa Dembele in Wednesday's defeat to AS Monaco.
The former Espanyol, Paris Saint-Germain and Argentina defender insisted he was not "killing" his squad, and explained how a conversation with his former boss and mentor Bielsa transformed his playing career.
"I was a person that liked the reality, that they never lied to me. If I was s---, I was s---. But I needed to know sometimes. When you are young, you need to know the reality. When you are in your bubble, you believe that all you do is right. And sometimes you need people who say, 'hey, come on, what happened with you?'
"I always remember Marcelo Bielsa when he arrived at Espanyol, in preseason. I was [rated as Spanish newspaper] Mundo Deportivo's best centre-back in La Liga. He arrived and said to me, 'how do you judge, analyse, assess your last season?' I thought 'the manager asked me about my season and Mundo Deportivo says I am the best centre-back...'
"So, OK, from zero to 10, [my season was] maybe seven, eight? I was very humble. In my head it was 9 or 10! 'You were s---,' he said to me. And my face was like this," continued Pochettino, feigning shock.
"He said, 'because of this, this, this and this.' He showed me why. And he said, 'if you perform like this last season, then you cannot play for me and you cannot play in the national team.' It was tough for me. I drove to my house crying but, do you know, after the time, I recognised it was true.
"I was s---, I was s---! Yes! And then I played the  World Cup, when I made the penalty [against England's Michael Owen] that wasn't a penalty, got a big offer from Paris Saint-Germain to buy me and changed my life. When I believed I was the star man, maybe from the news or the people, this big offer never arrived for me.
"But when I changed in my mind and my lifestyle and realised this is the reality, the national team, Paris Saint-Germain and different teams wanted me. This is an example that sometimes, although they are young, we are here to be tough but to be right -- not to be tough to be horrible and aggressive. We try to give good advice. That is the most important thing."
Pochettino was speaking ahead of Tottenham's Premier League match against Sunderland on Sunday, when Mousa Dembele is expected to return to the team following suspension.
The Belgian midfielder's eye-gouge on Chelsea's Diego Costa in May suggested no shortage of aggression, and earned him a six-match ban.
Pochettino says Dembele knows he crossed a line and revealed his own craziest moment as a professional footballer.
"To be aggressive doesn't mean to punch someone. To be aggressive with the ball means when you have it at your feet, you want to score, you are determined to," explained Pochettino.
"He knows that one thing is to play aggressive, to tackle, to go always to the ball and be honest on the pitch. Another thing is to do what he did. He paid for that and it was difficult for us because he was an important player and then you miss the talent of him on the last few games.
"In the history of football many things like this happened. Remember Maradona in '82 in Spain, there was big, big kick to [a] Brazilian player. He was sent off in the World Cup. Maradona...one of the best players in the history, the top player.
"At Paris Saint-Germain, I was playing and I remember the striker was big and was bad. He was naughty, not great. My teammate was Gabby Heinze, who [later] played for Manchester United. I said to Gabby, 'the next time the ball comes in the air, please, move aside, let me challenge.' I jumped and put my feet here," continued Pochettino, grabbing the back of his neck with both hands.
"When I put the studs here, I closed my eyes, I said, 'What have I done?' Sent off! I said sorry, OK. I was 27-years-old, the captain of Paris Saint-Germain."
Dembele was introduced at half-time against Monaco, with Spurs already trailing 2-1, and he helped the hosts to a much-improved second half -- a 45 minutes that pleased Pochettino.
The Argentine admitted "responsibility" for the defeat at Wembley but he rejected the suggestion that it was a mistake to start Dembele on the bench.
"It's not a mistake. That is your opinion," Pochettino said, in response to the question from ESPN FC.
"I always try to show respect for your job, like you need to show [for mine]. I decided to pick 11 players. If your opinion is that I must play Dembele, or should play Dembele, that's your opinion. I respect your opinion. But it's never a mistake. To pick 11 players, when you have 25, it's a mistake to select one or another? It's your opinion -- 90,000 people have different opinions. It's not a mistake."
"It's your opinion, my opinion, Jesus', Simon's...," continued Pochettino, referring to his assistant Jesus Perez on his left and Tottenham's press officer to his right. "But I am every day with them. If I judge in the training sessions, 12 hours with the players, you need to trust more in my decisions. My decision is to try to win the game. You can criticise my plan for the game. You can criticise my tactics. You can criticise my 11. Afterwards. But before you never criticise to me.
"If Monaco was 4-0, like Stoke City, then it would be 'good decision to put in Son.' But if Son [Heung-Min] didn't score and we lost 4-0, it's 'Pochettino, you're crazy, why did you pick Son, or pick him?' It's easy. But I understand that it's football. Always I show respect to you, because that is your job. Like my job is to be right in my selection. And always we are very flexible when we take a decision.
"After four months that Dembele didn't compete. And he wasn't ready to play 90 minutes in a Champions League game, if you believe that. I explain [to you] because I want to explain, but I don't need to explain why."