Here is a run-down of the key battles...
Robin van Persie vs Raphael Varane
The young defender has been a revelation for Madrid since bursting into the side since the turn of the year, and stood out as a man for the big occasion with a trio of superb performances against Barcelona. Van Persie will be aware he missed some gilt-edged chances to give Manchester United a big advantage from the first leg, and will be keen to make amends at Old Trafford. Varane has shown no sign of being overawed by any occasion, and he will need to be at his best again to keep the prolific Dutchman at bay on Tuesday.
Tom Cleverley vs Cristiano Ronaldo
Without Phil Jones, Manchester United will be short of options to track Ronaldo, and Cleverley might get the nod in the middle of the park to drop deep and help his defence monitor the Portuguese forward despite it not being a natural role for the English midfielder. Ronaldo will, as always, have a free role, drifting around the Madrid attack to find space, and Cleverley will need to keep tabs on him at all times. If he can get close to matching Phil Jones' performance of three weeks ago, Cleverley will go a long way to helping his side win through.
Shinji Kagawa vs Alvaro Arbeloa
A hat trick against Norwich surely means that Kagawa will be in the starting line-up on Tuesday, with the Japanese player showing wonderful composure to take his chances on Saturday. Kagawa will likely start in a nominal left flank position, but will have plenty of freedom to come infield to try and create chances and get on the end of balls himself. Arbeloa will need to ensure he doesn't get space on the left, and communicate with his colleagues in the Madrid defence when Kagawa tracks infield, as the former Dortmund man has shown he can be deadly when arriving in the box unmarked to finish off moves.
Rio Ferdinand vs Karim Benzema
Ferdinand was left out of the match on Saturday to ensure he will be fresh for this encounter, and he will likely be paired with Jonny Evans in the heart of Manchester United's defence. Having scored at the Bernabeu, United have the edge going into the second leg, but that will only last as long as they can keep Madrid at bay. Both Benzema and Higuain have been short of form for Mourinho's side, but they are still very talented players, and Ferdinand and company will need to focus as much attention on the striker as they do on Cristiano Ronaldo.
Rafael vs Fabio Coentrao
The Brazilian full back was another man rested for United this weekend and will likely return to the starting line-up on Tuesday. Rafael had a shaky start in the first leg, frequently being caught out of position by Madrid's fast counters, but grew into the match impressively. Both he and Coentrao are very talented attacking full backs, and both will be key to adding width to their side's attacks in what could well start out as a cagey affair.
image: © Jan S0L0