David Beckham :
Sir Alex Ferguson was a great manager with a very bad temperament and he was very furious having lost the FA Cup in February,2003. According to him, Beckham was the main culprit for that loss and very unsatisfied with his performance. He vented out his frustration by kicking a boot towards him which hit Beckham on the head. The relations between both of them deteriorated since then and Beckham soon left United to join Real Madrid.