#3 Bryan Robson
Bryan Robson joined Manchester United five years before Sir Alex Ferguson took over as the club's manager in 1986. One of the greatest midfielders of his generation, Robson represented the club in 190 matches, and was part of the beginning of United's domination over the English Premier League.
Robson was a box-to-box midfielder, equally capable of dominating both halves of the pitch. He is also Manchester United's longest-serving captain, having won the Premier League twice before moving on to Middlesbrough in 1994.
Sir Alex recently included Robson in his best all-time Manchester United XI ahead of the Manchester derby.
"The midfield was probably a bit easier because you have [Roy] Keane, [Bryan] Robson and [Paul] Scholes - they were fantastic players - and [David] Beckham, [Cristiano] Ronaldo and [Ryan] Giggs," Ferguson told Sunday World (via Marca).
#2 Paul Scholes
One of the greatest midfielders of all-time, Paul Scholes ranks second on our list of the greatest mids to have played under Sir Alex Ferguson. Scholes spent his entire career at Manchester United, the only player on this list to have done so, making 711 appearances for the club.
Scholes is the second most decorated player to have played under Sir Alex, winning 11 Premier League titles, two Champions Leagues and four FA Cups. Scholes retired as a player in 2011 but returned just six months later to help Manchester United win the league. But the Red Devils fell short on goal difference to Manchester City.
He did play the 2012-13 season, Sir Alex Ferguson's last for the club, and retired thereafter. He scored 152 goals for the club and made 74 assists to cap off a great career.
#1 Roy Keane
The greatest midfielder to have played under Sir Alex Ferguson at Manchester United is Roy Keane. The defensive mid was a great captain and wore with his heart on his sleeve.
Keane captained Manchester United to a historic treble in the 1998-99 season. Although he was suspended for the final against Bayern Munich, Keane ensured United qualified for the decider by scoring in the semifinal against Juventus. Sir Alex termed Keane's performance against the Italian giants as one of the greatest performances he had ever seen.
Keane spent 13 years at the club from 1993 to 2006 making 471 appearances, the fourth-highest in the club's history. He won seven Premier League titles, a Champions League and four FA Cups during his time at the club. He left for Celtic in the 2006 January transfer window before retiring as a player six months later.