"Ronaldo is above the rest. If he keeps scoring in this rhythm and stays in this sort of form, he will prove to be the best. Ronaldo is better than George Best and Denis Law, who were two brilliant and great players in the history of United." – Johan Cryuff, April 2008.
First of all, before we go any further, Early Doors is NOT about to try and argue that Cristiano Ronaldo is Manchester United's greatest ever player.
During his spell at Old Trafford he did not show the iconic artistry of George Best or Eric Cantona; the team-lifting fury of Bryan Robson or Roy Keane; or the consistent longevity of Bobby Charlton or Ryan Giggs.
But, when all is said and done, when we look back on his career once it's finished, when we strip away all debates about ego and arrogance and just look and the stats and look at videos – we will end up calling Ronaldo one of the greatest footballers who has ever lived – unrivalled even by all the great names that have worn red at Old Trafford.
They say "better the devil you know", but tell that to the United fans who will be at the Bernabeu later tonight. Their hearts will no doubt beat a little faster, with a sense of dread, whenever number seven in white touches the ball, because they know better than most just what he is capable of.
Better the devil you know? Better not knowing what this ex-Red Devil can do.
Ronaldo arrived at United as a skinny teenage winger but left the club as phenomenon.
His final two seasons at the club were like nothing we had ever seen before or since in the Premier League. The Portuguese star dominated football pitches like a gladiator in a Hollywood epic. He slashed his way through all before him, scored and created goals, won matches, won battles, seemingly all by himself.
The scary thing is, since leaving England, he has only gotten better. He left for Real Madrid in the summer of 2009 for a staggering world record fee of £80 million. Amazingly that has proved to be bargain; if Real Madrid were to sell him tomorrow, they could double their money.
You could pick any number of games from the last few years to illustrate his class but how about just popping in the tape of last Saturday's match against Sevilla for starters?
After setting up Karim Benezma for the opener, Ronaldo then cut in from the right onto this *weaker* left foot and unleashed a bullet of a shot into the corner of the net to make it 2-0.
He scored his second just after half time, and then just before the hour mark picked the ball up just outside his own box, went on a storming run that made him look like a computer game character that had just benefited from the sprint button, laid the ball off, continued his run, and eventually tapped in for his hat-trick.
It was truly stunning to watch – the 20th hat-trick of his Real Madrid career. He could have scored more in a 4-1 win but was soon taken off after completing his treble and rested for tonight's game. Jose Mourinho won’t show United such mercy tonight.
With all due respect to Best and Law and Cantona and Charlton and Giggs and Keane – Ronaldo can, and does, do things that those players, as great as they were, simply could not.
People seem to want to resist his talent because they see Ronaldo as egotistical and arrogant. This is all a matter of perception - one man's arrogance is another man's self-belief after all - but Ronaldo's personality is by-and-large irrelevant. His job is to win football matches, not elections.
Neither should the debate as to how he matches us up against Lionel Messi sour his legacy either. Messi may well already be the greatest player that has ever lived. Ronaldo cannot be expected to have a control on anything the Barcelona star does.
We live in a world that looks back in awe on the greats in all fields of human endeavour, and there is always space for more than one towering genius: Mozart and Beethoven, Da Vinci and Michelangelo, Einstein and Newton. In time we will look back at Ronaldo and Messi with similar reverence.
Real Madrid are a team filled with international superstars but it says something about Ronaldo's abilities that Manchester United will be immensely confident of victory if they can limit his influence. If they can stop Ronaldo, they'll take their chances with everybody else.
Sir Alex Ferguson knows, the players know, the United fans know, that Ronaldo is a capable of doing so much more damage than anyone else on the pitch. It will be fascinating to watch how they try and stop him.
Ronaldo wasn't there long enough to stake his claim as Manchester United's greatest ever player, but he might just be the greatest player that's ever played for the club.
QUOTE THE DAY: "Now come on boys, believe in yourselves. We’re Manchester United; let’s have a go at them. We’re Manchester United, let’s have a go at them." – Not Alex Ferguson's pre-match words of inspiration, but the words of Matt Busby from 1968. It was half-time in the European Cup semi-final between Real Madrid and United at the Bernabeu and United were trailing 3-1. Paddy Crerand tells the story of the match to Andy Mitten in his latest blog. A must-read for all United fans, and a really-ought-to-read for everyone else.
FORIGEN VIEW: "If Manchester are able to stop Ronaldo and cut off Mesut Ozil’s passes, they should go through to the next round. It will be important for Alex Ferguson’s team to achieve at a minimum a draw in Madrid – Old Trafford will then be a good place to seal victory," Eurosport Germany's Christopher Hemscheidt is one of just eight of our European football experts to give his thoughts on tonight's match. Find out who Europe thinks will win the big tie.
COMING UP: We will be building up to the big match with numerous features throughout the day with Arsene Wenger and Jim White amongst those filing their thoughts. As well as the Real Madrid-United live we will also have live text commentary of tonight's other Champions League clash – it is one for the football hipsters - as Shakhtar Donetsk host Borussia Dortmund.