It all started off so friendly. A grand occasion, played between two historic teams in a manner worthy of Sir Matt Busby and Santiago Bernabeu.
Real Madrid manager Jose Mourinho said it should have been the final, while Manchester United's Sir Alex Ferguson unleashed an epic blast of his misty-eyed Euro-love in his programme notes:
"People ask me why I don't retire after so many years in the game, but how could anyone with an ounce of passion for football in their soul voluntarily walk away from the opportunity to be involved in this kind of occasion?"
Imagine him saying that about a trip to Stamford Bridge.
United tend to see their English rivals as an irritant that they must periodically swat away. Europe? Something else entirely. Majestic, romantic, somehow nobler than the domestic game. Just sharing a stage with Real Madrid validates them.
Cristiano Ronaldo received an extraordinary hero's welcome, given an ovation that extended beyond the kick-off. It was a strangely euphoric reception for a man who spent the first leg terrorising them - not that they should bear any ill-will towards a player who served them with distinction.
The goodwill lasted 56 minutes.
Nani leapt in the air, foot outstretched. His eyes were fixed on the ball, unaware that Alvaro Arbeloa's torso would arrive first.
Both players lay prone as Sergio Ramos clamoured for action and Robin van Persie jabbed an angry finger in the Spaniard's face.
A flashpoint, but few expected to see the card brandished by Cuneyt Cakir.
Anger, consternation, fury. Old Trafford's glorious sporting celebration transformed into a cauldron of outrage.
Having been physically restrained from confronting the fourth official, Ferguson geed up the crowd, producing the loudest noise of a cacophonous night.
Injustice, yes. But now it was time to batten down the hatches and see out a famous win.
Instead, the furore inspired Madrid, who scented blood and pounced.
Luka Modric levelled the tie with an extraordinary 25-yarder, before Ronaldo scored an apologetic tap-in that must count as the saddest goal ever to clinch a European tie.
United were superb before the red and after Ronaldo's winner. But a 15-minute swoon cost them their place in the competition.
To say the ref killed the game is to reject the possibility of United conceding none or one goal. If they could have picked a player to lose, it would have been Nani, who had been their least effective player.
Their job wasn't easy, but it was possible. Chelsea did it against Barcelona last season (they did concede once after John Terry's red card, but crucially scored twice). Indeed United had won their previous four Champions League matches in which they had been reduced in number.
Fergie's incandescent reaction, Rio Ferdinand's sarcastic applause and the confrontation of Cakir will dominate the back pages.
Ferguson wisely opted out of his press conference, while United's players were prevented from speaking in the post-match mixed zone.
But as righteous as their indignation may have been, a harsh red card was only part of the story of this European sob story.
Before the red, the game almost lived up to its cataclysmic billing. Goals might have been scarce, but here were two very good football teams playing close to the top of their game.
United chose to combat Real Madrid's counter-attacking power by doing the same themselves.
Fergie purred about "tales of 'derring-do'" but his teamsheet provided the first indication of a more hard-headed approach.
Dropping Wayne Rooney was a classic Fergie move, carrying echoes of his decision to bench Daivid Beckham 10 years earlier.
So too playing Ryan Giggs on the right. Where did that come from? The Welshman has hardly been seen out there since the 1999 final.
Nani played left and Danny Welbeck through the middle. Not for the first time, a Fergie selection that appeared decidedly iffy on paper looked much better on grass.
Giggs tore up and down the right, at one point bamboozling Fabio Coentrao gloriously, winning a corner that Nemanja Vidic headed against the post.
Welbeck caused Real problems, but missed two first-half chances to open the scoring.
The crackling atmosphere went up a notch when the hitherto excellent Madrid centre-backs froze and Sergio Ramos found his own net.
Then Nani saw a red card and United saw the red mist.
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