Roy Keane was a brilliant player.
The tough-tackling Irishman played for Manchester United from 1993 to 2005, making 480 appearances across that time frame.
He would help the club to 17 trophies and was a major reason for their success.
What made Keane so good was his burning desire to win.
Keane gave absolutely everything on the pitch and couldn't accept losing.
This was sometimes his downfall. He had a poor disciplinary record, having recorded 69 yellow cards and seven red cards in the Premier League.
He often lost his head on the pitch and, according to Rio Ferdinand, he also used to lose his temper in training too.
Speaking on the VIBE with FIVE podcast, Ferdinand recalled how Keane punched Chris Eagles, who was only young at the time, in the face.
"I remember when Roy Keane punched up Chris Eagles one time," Ferdinand said.
"He (Eagles) was only [a] young kid, (taking) liberties. It was good for him, Eagles.
"Roy must have been coming back from an injury, or he didn't play, and he was playing with the reserves and the youngsters that were in there like Eagles and Lee Martin were like rats, getting in close and trying to tackle.
"He went in late on Roy once or twice and Roy said to him, "Listen, slow down". The ball comes in again, Eagles was trying to impress, trying to leave his mark and left a little bit on Roy again and pulled his jersey.
"Roy just turned round and went bang in the jaw."
Ferdinand wasn't best pleased with Keane and made sure to confront him about it.
He added: "A quick short jab and I just stood there and went, 'Roy, what's wrong with you?'.
"And I went inside and said, 'Roy, why are you doing that for? He's a young kid man. And I warned him.'"
Fair play to Ferdinand. Keane's actions were clearly out of order.
Eagles was only a youngster trying to impress so he could turn out for the first team.
Unfortunately, he would never truly make it at United.
He made 17 appearances for the club before departing for Burnley in 2008.
Now 35, he ha been without a club since leaving Oldham in January 2020.