During his scarcely believable 27-year stint at Old Trafford, iconic former Manchester United manager Sir Alex Ferguson enjoyed unprecedented success.
Recovering from a less than impressive start after his arrival from Scottish club Aberdeen, 'Fergie' brought a plethora of silverware to the North West and cemented a reputation as arguably the greatest football manager the world - and certainly the Premier League - has ever seen.
Despite him being most fondly remembered for his unrivalled success, Ferguson was also renowned for using so-called 'mind games' to unsettle his managerial colleagues and as such entered into a number of entertaining rivalries over the years.
Here, GMS lists Ferguson's five most enthralling and infamous rivalries with his fellow managers during his career at United.
Please feel free to comment on our selections and leave your own below...