When it comes to football managers, there weren't many better than Sir Alex Ferguson.
The Scottish genius transformed Manchester United into a perennial European powerhouse and possibly the most recognisable football team on the planet.
He was the man behind some of the finest squads the England top flight has ever known, winning a staggering 13 Premier League titles and two UEFA Champions Leagues.
He did, however, have a notoriously short fuse, and at the end of that fuse was a thunderous temper unlike any other.
Just ask David Beckham, who had a boot flung his way by the Scot after a spat in the dressing room.
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Now, former England boss Sven-Goran Eriksson has revealed another story about Fergie's famous temper, and how the Swede's decision to select Wayne Rooney always lead to a row.
Speaking in an interview with the Times, Sven outlined how a standard international break conversation would go with the fiery Scot.
"With Alex, the amazing thing was it was seven o’clock in the morning or earlier. Always. When he was angry.
"And never 'Hello Sven, how are you?' It was “whuurssshhhh” [yelling]. I thought he should kill me.
He said, 'I will kill you. You are finished.'
"But I represented England and you have to stand up.
"What’s right is right and what’s wrong is wrong and when you say 'Don’t pick Rooney because I’m going to kill you'... I said, 'F*** off, what’s going on with you?'
"And he was screaming. Whenever he got like that... it has no meaning.
"That’s why I was, 'Alex, I will pick Rooney. Now, have a nice holiday. Ciao, bye'".
Credit to Sven for standing up for himself though, many may have backed down in the face of such a verbal onslaught from a managerial titan like Sir Alex.
In the end, Rooney's selection mattered little as England failed to even make a dent on the international scene while United continued winning titles for free.
It would still have been pretty special to be a fly on the wall when Sven hung up on Ferguson, though - just imagine the explosion.