Sir Alex Ferguson ensured that his Manchester United teams only had "animals" for winning in the squad, Rio Ferdinand has said, citing that as the key to so much success.
The Scot won two Champions Leagues and 13 league titles at Old Trafford, with Ferdinand at the heart of seven of those major trophies.
Speaking to ESPN FC at BT Sport in London about what he perceives has been a drop in Premier League quality this season, the pundit and former centre-half believes that intensity and focus has been something many teams struggle to replicate.
"Ferguson got rid of players who didn't buy into the Man United way, for one, or weren't capable of being intense every day," Ferdinand said from the BT green room, where he was analysing the Champions League.
"That's why you don't remain at a place like Man United. If you're not an animal who can go in there and be intense every day and demand from yourself and others to improve, you won't stay long... and good riddance."
Ferdinand said that is an attitude that initially comes from the manager, but that is taken on by players, who then set a standard for the rest. He cited his own example as someone who saw it from both sides, the young player learning from Roy Keane, Ryan Giggs and Paul Scholes on first signing for United from Leeds United in 2002; and then the senior professional showing others how to handle such situations.
"It comes from the manager, I think, and the players identify that and then go and start playing that out on a regular basis, but I think obviously you need the manager to set the tone, and then the experience being able to deal with it," Ferdinand said.
"I came in to a squad [in 2002] experienced at winning. For example, when I came in, I never knew how to win. I was looking around like a sponge and I had Roy Keane, Giggsy, Scholesie in that dressing room.
"And if there's a point in the season where I thought, 'Oh, gotta win this one, is it a nervous time, or are you meant to be remain chilled, or what?' You're looking at these lads, and they're preparing the same every game; they're just focused every game, every day in training.
"Focused. That's the difference, having people like that who understand it and know it.
"And, what happens, I've been there. I was the one who learned, and I was the one who showed the way, so I've done both sides. I know you're not born with it but there's got to be someone in that changing room who you go to because he looks like he's so comfortable with the situation, knows it. I'll follow that."
That attitude eventually made United feel "invincible" at their peak in winning the league and Champions League in 2007-08, Ferdinand explained.
"You've got to look around the changing room and think 'I can rely on him', he's going to produce big moments," he said. "Teams can't deal with him. They can't score past us. When you start feeling like that, you feel invincible. That breeds confidence."