For a side playing at home with the attacking dominance right across the pitch that Los Blancos have, Sir Alex Ferguson will no doubt be a very happy manager after watching his side concede just one goal and, most importantly, pick up a draw at the Bernabeu Stadium.
Madrid have a multi-faceted attack that few other teams can boast of in world football, and they have achieved great success because of it.
So to only concede the once and really, not give up that many goal-scoring chances to a very dominant and complete attack is really a strong performance form the Red Devils' defense and one that they will no doubt feel very proud about.
Having said all of that, there is little doubt that United got seriously lucky in this one—starting with the brilliance of David de Gea at the back.
Without their shot-stopper having arguably the greatest game he's ever had in a United shirt, Madrid would surely have found the back of the net more than once here and could well be taking a two or three-goal lead into the Old Trafford fixture.
He was head and shoulders above any other United player here, and could not be faulted on the night for anything that he did, which is a rare occurrence for De Gea.
The Red Devils need to be careful not to over rely on De Gea when they tackle Madrid again in three weeks' time; they must know the threat that Madrid possess even away from home and be just as switched on there as they were in Spain.
They must recognize the areas in which they were lacking defensively in the opening leg and aim to correct those for the final leg, with the biggest issue coming out at right-back with young Brazilian international Rafael Da Silva.
The youngster provides a great attacking threat for United out on the right and has improved dramatically throughout 2013, but was shown almost to be a boy playing against men in this one—especially against Ronaldo.
He was beaten several times by the Portuguese international as well as Angel Di Maria when they switched wings, and should have done better in cutting off crosses into the box—like the one that Ronaldo netted Madrid's only goal from.
If United are going to win the second leg—which they'll need to do to progress—they cannot do it if Rafael is at the back on the right flank.
They don't need his attacking threat per se in this one; what they need more is defensive solidity, which Rafael cannot offer the Red Devils as much.
Should the Brazilian international be on the bench then, various scenarios open up for potential inclusions at right-back for United—the most likely of which is Phil Jones, who did an excellent job marking Ronaldo throughout this one.
Playing him at right-back works, and allowing him to continue his role of sticking with the superstar winger should also work for United. If he drifts in, then the other defensive midfielder or even the right-winger can drop back to cover for him.
Antonio Valencia needs to start on the right-wing—a place where he can offer a better offensive threat on the wing and also where he can drop back and cover Jones at right-back. The Ecuadorian's defensive skills are very solid and he could even be utilized as a right defender by Ferguson if need be in this one. That's how good he is defensively.
In terms of the central midfielder coming across to cover for Evans when Ronaldo comes infield, United have two main options here. They could opt for Michael Carrick, who did a nice job sliding in to central defense to help out in the first leg, or they could even look to use Jonny Evans, who started the match in replace for Nemanja Vidic at right-back.
Rio Ferdinand proved that he is more than capable of stepping up here and won't be beaten goal-side, so with Vidic's impending return, Evans could very well be free to play the roaming role that Jones played so well throughout the first match.
With essentially three centre-backs in operation then, Tom Cleverley makes sense as the most likely other central midfielder given his attacking presence.
United will need some go forward from the middle, which they didn't have at all in this one, and Cleverley would no doubt provide that in this one.
Expect him to partner well with Wayne Rooney (similar to Jack Wilshere and Santi Cazorla to an extent) and provide the Red Devils' strikers with plenty of opportunities.
However it might look, United need to make defensive changes to ensure that they aren't relying on the brilliance of De Gea again not to lose this one.
They did well to hold out Ronaldo once, but they did allow chances through the middle of the pitch that could have otherwise been avoided. Look for some big defensive changes from Ferguson when Madrid come to Old Trafford in March to ensure that the Red Devils march on in the Champions League.
What changes do you think need to be made by Manchester United?
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