Roy Keane is widely considered one of the most terrifying players of the Premier League era.
Although he wasn’t the biggest footballer - he was under 6ft and not particularly imposing in a physical sense - the former Manchester United captain took no prisoners on the pitch.
He was an absolute warrior who, when he deemed it necessary, was more than happy crossing the line between firm but fair and violent. Just ask Alf-Inge Haaland.
But it turns out that it wasn’t just opposition players who Keane managed to intimidate during his illustrious career.
Former Premier League referee Mark Clattenburg has revealed what happened the first time he took charge of a match involving the fiery Irishman.
Clattenburg on his first meeting with Roy Keane
“Even in the Premier League, I still smile at the first time I came across Roy Keane,” Clattenburg told NBC’s Men In Blazers podcast, per Balls.ie.
“He screamed at us for a corner and I'm sure it was a goal kick but because he screamed at us so loudly, I gave a corner, I was that petrified of him.”
No offence, Mark, but that’s an embarrassing admission for a professional referee to make.
Can you imagine someone like Pierluigi Collina deliberately making a wrong decision in a football match because a player shouted at him?
It just wouldn’t happen.
Referees are there to ensure the laws of the game are implemented and Clattenburg, who took charge of the Euro 2016 final and the Champions League final in the same year, failed to do his job on that occasion.
Clattenburg admits he lacked man management skills early on
It was clearly a character building experience for Clattenburg, who did go on to reach the very top of his profession.
"I probably lacked man management,” Clattenburg admits about the early years of his refereeing career. “I didn't have management experience because I was still a young boy. I hadn't had that employment background. I didn't have any experience of dealing with people, managing people, saying the right thing at the right time.
"It's only when I got older that I started to develop those skills. When you have those skills, you interact with adults better, players better. If you interact with players, they make your life easier. When they make your life easier, you become a good referee."