Manchester United manager Sir Alex Ferguson's biggest mistake during his 26-year reign at Old Trafford was allowing Paul Pogba and Ravel Morrison to leave the club.
The two starlets have made headlines in recent weeks after impressing for Juventus and West Ham respectively, making Ferguson's decision to let the duo go even more baffling.
United's midfield is the one area of the team that has needed improving even when the Premier League champions have dominated in Europe and England.
In fact, the Red Devils' midfield has never been the same since the 1998-99 season when Ferguson's side won the treble.
The legendary manager was able to call on the services of four world class players in Roy Keane, Paul Scholes, David Beckham and Ryan Giggs.
All four players brought a different skill and quality to Ferguson's team.
Keane's determination, Scholes' passing, Beckham's delivery and Giggs' dribbling ability allowed United to dominate games against Europe's top sides.
United's midfield ever since the aforementioned quartet went their separate ways has never been the same.
The Red Devils heavily relied on Scholes during his last few years at the club, which was not ideal considering the United legend was unable to play every game.
However I believe United could have had a midfield that could have become even better than what they had in 1999 if Ferguson had convinced Pogba and Morrison to stay.
Ferguson admitted to his close friends that England Under-21 star Morrison was the best player to come out of the academy since Scholes progressed through the ranks in the 90s.
However, despite his undoubted talent, Ferguson allowed Morrison to leave for West Ham United - where he has gone from strength to strength in recent weeks.
Losing Pogba to Juventus was an even bigger blow to United as the 20-year-old midfielder would have slotted in nicely next to Michael Carrick.
United fought tooth and nail to sign Pogba from Le Havre only to see him leave on a free transfer.
We will never know the true answer but surely a central midfield partnership of Pogba and Morrison along with Wilfried Zaha and Adnan Januzaj on the wings would have had the potential to be as good as the stars of 99.