Yet, as crazy as it might seem given the superstar pedigree that Ronaldo currently has, the Red Devils could well shut down the Portuguese international entirely.
The 28-year-old is a former Manchester United winger, and therefore Sir Alex Ferguson knows much of his game and his greatest strengths and weaknesses. That in itself will not stop Ronaldo, for little has slowed down the superstar so far in his remarkable career.
The point must be made that no team in the history of world football has ever been able to completely shut down Ronaldo.
The winger is simply too good on the ball and too good in space to completely shut him out—regardless of how hard the Red Devils might try.
Yet what they can do is reduce his impact on the wing, bringing him into the middle of the field where United can get its best defenders in his face—forcing him into errors or turnovers that we otherwise wouldn't have seen from the Madrid star.
Much like he did with Gareth Bale earlier in the year, expect Ferguson to use Rafael Da Silva as more of a shadowing defender in this first leg.
United will know that a draw gives them the advantage in the second leg, so they don't need to use Rafael's attacking skills as much here. Therefore, they can sacrifice him in attack and allow him to sit deeper on the right flank against Ronaldo.
The key for United will be how they get a defensive midfielder back into the fray to help Rafael deal with Ronaldo when he cuts in to his right foot.
Against Spurs, it was Phil Jones who slid in to cover the Welsh winger, and United would seemingly do well to play a similar style against Ronaldo here.
Tom Cleverley is the most logical assumption here, but don't be surprised to see Michael Carrick deployed either. The junior of the pair has a much more physical presence in his game compared to Carrick, which could result in unnecessary free kicks—which is the last thing United will want to give to the Portuguese international in this one.
Carrick is experienced, particularly in the Champions League as well as with Ronaldo himself, and could be used to slip in here for that defensive midfielders' role.
Also don't be surprised to see Rio Ferdinand either rested here or swapped with Nemanja Vidic in central midfield in terms of the territory they cover.
The England international isn't as quick as he used to be, and given the fact that he would most likely be needed to come over and cover Rafael down the line, Ferguson may opt to either use the pace of Chris Smalling or Jonny Evans (assuming oath are healthy). He may also just swap the two central defenders around so that it is Vidic sliding over to help Rafael and not Ferdinand.
Either way, the ability for United to get Rafael goal-side of Ronaldo and slide the defensive midfielder over to cover when he cuts in will be key here.
If the Red Devils can effectively do that, Ronaldo may well push infield more and allow the Red Devils a better chance of nullifying him even further.
Of course, that won't completely do away with his impact and significance here, but it could well go a long way to United not losing this match and placing itself in a strong position for the return fixture at Old Trafford next week.
There are some dangers with this, and Ferdinand himself alluded to the biggest one of them all earlier this week via The Telegraph.
We are going to have to use all of our experience, courage and ability to make sure that we stop not only Ronaldo, but the other players they have because Real are a great team. They have so many other weapons. We could shut Ronaldo down for 90 minutes, but they still have players to hurt us, so we have to be compact and work hard.
Yet at one level, you almost think that it's a problem United would be willing to have—dealing with other attacking options because they've done away with Ronaldo's impact in the game.
After all, the Portuguese winger has netted 136 goals in just 123 games for Real Madrid in his career and has 30 goals from just 28 appearances this year.
Any sort of dent they can make in that will no doubt go a long way here.
Especially if, like Bale, they can get him scoreless on the night.
How should Manchester United try and shut down Cristiano Ronaldo?
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