Manchester United v Schalke - key battles
Dimitar Berbatov v Manuel Neuer
Berbatov is still the Premier League's leading scorer, but the Bulgarian striker has not been as prolific as late. The indications are that Berbatov will start against Schalke and he will have to be at his sharpest to beat Neuer. The Germany goalkeeper produced one of the best displays ever seen in the Champions League in the first leg, but still ended up on the losing side. He remains the only reason Schalke still have a slight chance of making the final.
Nemanja Vidic v Raul
Vidic hardly gave Raul a sniff of a chance in the first leg, but the 33-year-old Spaniard has enough experience in the competition for United's defence to be wary of him. His 71 Champions League goals and three winners' medals from his time with Real Madrid tell their own story. However, Vidic has been superb this season and it will be a big surprise if he does not emerge on top again.
Michael Carrick v Joel Matip
Still only 19, defensive midfielder Matip was simply swept away by the United hordes in the first leg and needs to be more authoritative to prevent the same thing happening at Old Trafford. Carrick struggled against Arsenal on Sunday but this European contest may be more to his liking.