Alf-Inge Haaland, father of Erling, is best known for his feud with Roy Keane.
The bad blood between the two started in 1997 in a match between Leeds and Manchester United.
Keane went down in agony after a tussle with Haaland.
The Norwegian turned around and stood over Keane, shouting at him and accusing him of feigning injury.
It was later revealed that Keane ruptured his ACL.
Keane never forgot Haaland's actions. He got his revenge four years later in a match between Man United and Man City.
The Irishman produced one of the most infamous tackles in Premier League history as he completely wiped out his opponent.
He then imitated Haaland's actions, shouting at him and accusing him of feigning injury. He was sent off but, to Keane, that did not matter at all.
Remarkably, Haaland was able to finish the match. He would play for Norway four days later and then start for Man City in their next game.
But, despite that fact, former Man City chairman David Bernstein believes it is 'appalling' that Keane still works in football.
He told The Athletic: "I've never forgotten it. From a personal point of view, that was the worst individual thing I've been directly involved in, and the worst I've ever seen on the pitch.
"As a human being, it was an awful thing to see. Roy Keane stood over him and basically said, 'Take that, you b******.'
"It was done in cold blood. I have never forgiven Keane for that. I think, frankly, it's dreadful he's accepted in football the way he is. After doing something like that, I think it's absolutely appalling.
"Whenever Keane turns up on television, I switch off. I just won't watch it.
"I'm appalled that he's still involved with football. It's just not right.
"Things happen, injuries do happen, but to do it deliberately and admit it the way he did, to sell his book, I think is completely beyond the pale."
The challenge is now 20 years on but it's arguably still the worst in Premier League history.