Arsene Wenger surpassed Ferguson's 7,582 days in charge on Monday and is now out in front on his own with an incredible 7,585 days.
Former United boss Ferguson brought the curtain down on an illustrious career with a 5-5 draw with West Brom in May 2013, with United new boy Romelu Lukaku scoring a hat-trick for the Midlanders.
Ferguson started his United tenure in 1986, though the Premier League did not come into existence until 1992. Wenger on the other hand joined the Premier League party 4 years late, making the move in 1996, after leaving Japanese outfit Nagoya Grampus Eight.
The Pair are well out in front in the list of longest Premier League managerial reigns, with David Moyes their closest competitor after spending 4,82 days at Everton between March 2002 and May 2013.