Sir Alex Ferguson describes former Manchester United player Roy Keane as having "the most savage tongue you can imagine" in his autobiography.
Addressing the infamous incident when Keane publicly criticised his team-mates on the club's television channel, and him subsequently leaving the club, Sir Alex told ITV News' Mark Austin:
"It was a savage attack on the players. No doubt about that. I was left with having to make the decision about what to do with it.
"I had a great relationship with Roy right up until that summer we went to Portugal....but he overstepped his mark. And what do you do?
"The players would have thought very poorly of me if I hadn't done something that day".