Fergie flips as Nani sees red in Real victory.
A night that began with the shock of Wayne Rooney's omission, ended in bitter frustration and recrimination as Luka Modric and Cristiano Ronaldo sent Real Madrid into the last eight.
It was the controversial dismissal of Nani for a second-half foul on former Liverpool man Alvaro Arbeloa that was the talking point.
At the time, United were leading through Sergio Ramos' own-goal and 2-1 up in the tie.
The pivotal decision of Turkish referee Cuneyt Cakir turned all those hopes to dust.
Rio Ferdinand summed up the mood around Old Trafford when he petulantly applauded in the referee's face after it was all over.
United took the lead shortly after the interval. Rafael's surge to the edge of the box had Real floundering and although Van Persie's shot was deflected away from goal, Nani's cross struck Ramos and rolled into the net.
And then the roof caved in.
Nani challenged Arbeloa for a bouncing ball inside his own half, with his foot crashing into the Spaniard's ribs.
Modric struck first, with a viciously curling effort from 25 yards.
Three minutes later Mesut Ozil found Gonzalo Higuain, whose cross was turned home at the far post by the man United must have known would score.
MELTDOWN: Alex Ferguson