While certain stars like David de Gea, Rafael, and Robin van Persie are certainties to feature against Real Madrid, the rest of Sir Alex Ferguson's team selection isn't quite as straightforward.
Here are three big choices the manager has to make ahead of kick-off...
How to compensate for Phil Jones' injury?
The news Phil Jones will miss the clash with injury is a big blow to United. Jones was hugely effective for United in the tie at the Bernabeu, acting as a spoiler in midfield effectively. It's a role United would otherwise have pegged Darren Fletcher for, who is also ruled out with longstanding illness. So United need to think differently, clearly Michael Carrick is a starter, but United need to consider which if any of Cleverley or Anderson merit starts in midfield, with Scholes also ruled out. One option for Ferguson is to play Ryan Giggs in the centre, and this may just be his choice, with the Welshman rested at the weekend. United could also ask Wayne Rooney to play a deeper role to compensate and help them out.
Does Shinji Kagawa merit a start and where?
Shinji Kagawa was bought just for games like this, to unlock defences in crunch encounters, and his weekend hattrick against Norwich could have been perfectly timed. He will be full of confidence and determined to make an impression in the biggest match of his United career to date. He started on the left in the Bernabeu but had little effect, but United should enjoy more possession tonight and the game is likely to be more open and less cagey due to the nature of it being a second leg and they need to find a space for Kagawa. Fortunately his versatility means he can play in a number of positions, and while it's probable he will start on the left again, don't be surprised if he ends up on the right or in the centre.
Who starts in central defence?
Jonny Evans was perhaps a surprise starter in the Bernabeu, as United were forced to break up the Vidic-Ferdinand axis which has been their cornerstone in recent years. Over the past 12 months though, Evans has been a regular in defence, and it's hard to imagine him being dropped especially considering his excellent form of late. This leaves a question over which of Vidic or Ferdinand should partner him, and we wouldn't be surprised to see Vidic miss out again.
What do you expect United to do?
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