Sir Alex Ferguson may step down as Manchester United manager this week.
We are witnessing the final days of Sir Alex Ferguson’s incredible 27-year reign at Old Trafford, what has been his greatest achievement?
That first title in 1993, the first double a year later, the unprecedented Treble of 1999 or the Premier League and Champions League double in 2008?
None of the above.
Ferguson’s greatest achievement was winning the Premier League title and reaching the Champions League final in the 2010-11 season.
That season’s success belonged entirely to him.
All his previous successes had been won with the help of some truly great teams and players, including Eric Cantona, Roy Keane, Peter Schmeichel and Cristiano Ronaldo.
But in the 2010-11 season, it was the sheer force of his personality that pushed a distinctly average United side to the title.
During that season, bolstered only by the modest arrivals of Chris Smalling, Javier Hernandez and Bebe in the summer, United’s midfield looked unstaffed, their defence vulnerable and they had to deal with their best player, Wayne Rooney, announcing mid-season he wanted to leave.
But only Ferguson could have taken that group of players to the title and one game away from being European champions.
Since the departure of Cristiano Ronaldo in 2009, without ever properly replacing him or spending the £80 million raised, Ferguson has won the Premier League title twice, in 2011 and 2013, and finished runners-up by a point in 2010 and goal difference in 2012.
Increasingly in his later years, it is Ferguson in the dugout, rather than any player on the pitch, that has been the difference.
It is Ferguson’s all consuming determination and will to win that makes average players good, and good players great.
Without Ferguson, United will be a far weaker team next season.
Without Ferguson, this current United squad will lose the ultimate safety net and need significant investment in the summer.
A new manager, whether it is Jose Mourinho, David Moyes or someone else, will not be able to win the title with the existing squad.
To counteract the sense of loss United may need to give their new manager a bold welcoming gift, a Radamel Falcao, Robert Lewandowski or even the return of Cristiano Ronaldo.
Something big, something extraordinary to start the new era.
A new manager would also instantly change the status of every single player at the club: Favourites would be banished and outsiders brought back into the fold.
Will David De Gea be deemed a risk not worth pursuing?
Will Rio Ferdinand be ushered out before he gets to enjoy his testimonial?
Will a new manager see Danny Welbeck and Tom Cleverley for what they could be: unfulfilled potential destined never to fully bloom?
Will Nani be given the love and attention he so clearly needs and craves?
These questions will be answered when the post-Ferguson era begins, but what is certain is a new manager will seek to stamp his own personality on United and bring in players he has already worked with and trusts.
Manchester United are set to experience a level of change they have not known since November 1986.
We always knew it would happen one day, but it still feels remarkable to be even contemplating Manchester United without Ferguson.
His name will forever be etched on his stand opposite the manager’s dugout at Old Trafford, while his bronze statue stands outside above the entrance.
But inside Old Trafford next season, United will be without the most influential figure in their history, and for once, the club's future seems strangely uncertain.