Occasionally in football, you witness moments where loyalties stray from the subconscious and an appreciation of what has just unfolded can be nothing but admired.
In essence, it takes something spectacularly special for a home crowd to rise, on all four sides, and applaud an opposition player during a season-defining knockout tie.
But in April 2003, a Brazilian by the nickname El Fenomeno lived up to his billing at Old Trafford. This was the night Ronaldo - the original - produced his greatest Champions League performance, on the grandest of quarter-final stages.
In attempting to overcome a 3-1 first-leg deficit after a humbling evening two weeks previously at the Bernabeu, United were pinning dreams of a Champions League final in their own backyard on that intrinsic resoluteness which had defined Sir Alex Ferguson's time at the club. Barcelona 1999, and all that.
Madrid, meanwhile, at the fulcrum of the first stint of Florentino Perez's Galacticos, were looking to become the first team to defend Europe's greatest prize since its 1992 rebranding.
Could United, amidst a vintage Premier League title dogfight against Arsenal, mount a comeback which had become synonymous with Ferguson's all-conquering squad over the years?
If they could, it would seemingly be without David Beckham. A shock selection decision: benched, in favour of notorious substitute Ole Gunnar Solskjaer on the right-hand side.
Ferguson's message - two months after boot-gate - was clear and that summer, Beckham would join Los Blancos.
On the night in question, as it happens, Beckham would have his moment in the spotlight. An audition of sorts. But it'd be too late. Because 12 minutes in, Ronaldo wiped out United's away goal lifeline into oblivion... and was only just getting started.
After stealing a march on Rio Ferdinand and running on to a threaded pass by Guti, the 26-year-old World Cup winner clinically finished low past another world champion Fabien Barthez at his near post.
United rallied, as they always did, and Ruud Van Nistelrooy's predatory instincts meant it was level at the break and United were only two goals short of levelling the tie. Still in it, just.
But Madrid, with superstars in just about every single position on the pitch, oozed class and composure as they steamrolled their opponents from the off in the second-half.
Zinedine Zidane, at this point the most expensive player on the planet, was afforded too much time outside the box, and not a single player decided to track Roberto Carlos, unanimously the best left back in the world.
In the box Carlos strode, and a simple pass across to his compatriot for a tap-in crushed United's hopes in reality. With Madrid leading 5-2 on aggregate, the Red Devils now needed four.
Although they fortuitously snatched one two minutes later, with the score on the night level again courtesy of an own goal by Madrid centre back Ivan Helguera, Ronaldo was inexorable. It'd be his name on Thursday's back pages.
Receiving the ball with his back to goal, just outside the centre-circle in the United half, Ronaldo inched forward, feigned left and effortlessly found half-a-yard shaping on to his right foot.
Twenty-five yards out, he struck the ball ferociously on his instep with the laces into the far corner, the ball whizzing past another despairing Barthez dive.
'Pick that out! What a hat-trick! And what a stage in which to score it,' bellowed lead ITV commentator Clive Tyldesley. The man sitting next to him, former United boss Ron Atkinson, simply commented: 'He's unreal ain't he.' He certainly was, most glowingly on that night.
Four minutes later, Beckham came on with the tie settled beyond all doubt. Another four minutes had elapsed when Madrid's esteemed boss Vincente Del Bosque cranked down the gears and substituted the star of the show.
No booing. No venting of frustration. A dignified response from the Old Trafford faithful; an acceptance of Ronaldo's majesty.
Beckham would go on to say afterwards: 'The whole crowd got to their feet and gave the bloke the kind of ovation a United player would have got. The Manchester crowd knows its football and knew they'd been privileged to be there, watching Ronaldo play.'
And yet this glorious feast of attacking football wasn't complete. Time for Madrid's next marquee acquisition to pass his audition.
First, a Beckham special. A free-kick, five yards outside the box, to the right of the penalty area. That recognisable one whip of the right foot, up and down over the wall and into the net. Iker Casillas, who'd made save after save all evening, did not move.
All in consolation no doubt, but Beckham even grabbed a second, pouncing on a deflection to poke home on the line. By this stage, with five minutes to go, United led 4-3 on the night, but were still two goals short of saving themselves.
Not enough time was left on the clock and it was Madrid who went through to the semi-finals, where their European streak would become unstuck against Juventus.
Nevertheless, both sets of supporters had witnessed a mouthwatering night of splendid goals. In an era where the defensive robustness of Jose Mourinho and Rafael Benitez loomed on the horizon, this was 90 minutes of frenetic, free-flowing action of the highest order.
It was so enthralling, in fact, that it convinced one keen observer in the stands that he fancied a little bit of this. Two months later, Roman Abramovich bought Chelsea Football Club for £140million.
But beyond all the characters in this tale, perhaps the last word should go to Ferguson, who remarked afterwards: 'What a game - Ronaldo was marvellous. His third goal was a tremendous strike and you can't legislate for someone who produces moments like that.'
Even after defeat, the master of footballing triumphs had no choice but to salute the individual brilliance he had witnessed. Marks of respect don't get much greater.