The last time a Ronaldo played against Manchester United he produced a masterclass in goalscoring and almost single-handedly silenced the home crowd. That was the original R9; the Brazilian Ronaldo, who has now fallen from grace but scored a hat-trick that night at Old Trafford to put the tie out of reach for Sir Alex Ferguson's men.
Ronaldo had not long before the clash been awarded with FIFA's World Player of the Year award and was wholly expected to cause problems for United, but his three goal haul may even have been beyond his expectations.
This time around, we have a new Ronaldo to laud. Cristiano faces his former employers for the first time since his world record £80m move to Madrid, and were it not for the existence of Lionel Messi, United would once again be set to face a Ronaldo that is better than every other footballer on the planet.
That he is not the best player around will not be any consolation for Ferguson and his team, but that Real could only finish second in their Champions League group - albeit a tough one - and are third in La Liga at the moment, could provide reason enough for United to feel confident ahead of their upcoming tie. Here we take a look at where the key clashes will be at the Bernabeu on Wednesday evening.
Cristiano Ronaldo vs Rafael
It is rarely Alex Ferguson's gameplan to set out and defend, and given their strength on the front foot there is no reason to expect this match to be any different. Nevertheless, first and foremost in his mind could well be how he might stop his former prodigy. He knows the Portugal captain better than most and the recent performances of his right-back Rafael may give him more confidence of being able to stunt the threat of the winger.
Ronaldo's game has a great many aspects to it, but as he exhibited perfectly with the first of his three goals against Sevilla this weekend, much of his threat comes when coming in off the flank - whichever one he happens to be occupying at the time - and letting rip from distance. And it is not as if he only does so against lesser opposition. His average of 7.5 shots per game in La Liga is only slightly more than the 6.2 he had in the Champions League group stage, against Ajax, Man City and Dortmund. Both are by far and away the most by any player in their respective competitions, and his 30 goals in 28 appearances across the two is only bettered by his nemesis, Lionel Messi.
Blocking shots is not Rafael's game, though. The Brazilian has only blocked 5 shots all season in the Premier League, but he prefers to get to his opponents before they get the chance to shoot; he has made 68 tackles this season, the 4th most by any defender in the English top flight, whilst also making an impressive 41 interceptions.
It may, however, be Ferguson's choice to tell Rafael to push on and try to peg Ronaldo back. The right-back does like a forward foray, and with 2 goals and 3 assists in league games this season, he and teammate Patrice Evra (9 goals/assists) make up the most attack-minded full-back pairing in the Premier League. Ronaldo offers very little in a defensive sense and while Rafael's attacks could leave gaps at the back for Real to exploit, United tend to prefer attack as the best form of defence and will probably stick to their guns in that sense, though some caution would probably be for the best.
Robin van Persie vs Pepe
Robin van Persie's instant impact for Manchester United has not wavered in the slightest. Now on 22 goals in the league and Champions League, he will carry the main threat for the Red Devils at the Bernebeu. Partnering Sergio Ramos at the back for the Whites is likely to be Pepe, who has only recently recovered from injury and may therefore be the chink in Real's armour that van Persie can look to exploit.
Pepe has been known to commit a few errors in his time and can certainly be hot-headed as well. He seems to have calmed down this season, with just 5 yellows and no red cards in 23 appearances in the Champions League and Primera, but needs to cut mistakes out of his game. Of course, players are not infallible, even at this level, and the pressure seems to get to Pepe at the wrong times. He has made 2 errors leading directly to a goal this season, and those have come at important times. The first was in the 2-2 draw at Camp Nou when he failed to clear his lines on the edge of his own 6 yard box to allow Messi to score, while the other came in the 2-1 Champions League defeat at Dortmund which eventually meant Real came second in the group.
Van Persie is a deadly finisher, and will pounce on any mistake Pepe might make. He and Wayne Rooney have begun to link up fantastically well in recent weeks, with both in the top 20 for Premier League goals and the top 10 for assists. Extra help from Sami Khedira will be necessary as Rooney drops deep to collect the ball and van Persie's clever movement makes him particularly difficult to pick up. Both can score from all manner of situations and Pepe and co will have to be on point to quash their threat.
Passmaster Battle - Xabi Alonso vs Michal Carrick
Both teams play fairly similar systems, at least in as far as they have a player who will patrol the area in front of the back four and try to dictate the pace of the game. Xabi Alonso and Michael Carrick will more often that not have more touches than other players; they respectively average 87.4 and 83.7 in this category in league games this season, so are clearly in possession with roughly the same frequency.
Xabi Alonso is possibly more ambitious in his play, averaging 29.5 forward passes per game to Carrick's 27.7, and though this is only a small difference, it may go some way to explaining Carrick's superior pass success rate, though such a marked difference - 87.7% compared to 81.4% - is extremely surprising. What might be even more surprising is Carrick's 4 assists compared to Alonso's 2. This is a meagre return for the former Liverpool man, and he should certainly look to improve that.
In a defensive sense, Alonso shines through. While Carrick (2.4) makes slightly more interceptions per game than Alonso (2) in league games this season, the Spaniard makes up for that with 3.5 tackles per game to Carrick's 2.3. Alonso is known for tough tackling as well as a wide range of passing, and his recklessness has seen him pick up 9 yellow cards in 20 Liga appearances.
These two will be key to which team can take control of proceedings at the Bernabeu, and it will certainly be interesting to see who can find the most space in which to operate.
Find our match preview of Real Madrid vs Manchester United here