#1 Ending Barcelona's unbeaten run

By far the best motivation you can give any Madrid player before walking onto the pitch - they have the opportunity of spoiling Barcelona's 'invicible' season. Even more so, considering that they are the last real challenge the Catalans must face this season.
If Barcelona don't go in the lead early, not wanting to lose could significantly influence their performance. The Blaugrana are at their best when they can play free-flowing attacking football. Should the fear of defeat come across their minds during the match, it could spell their downfall.
Real, on the other hand, will not want to see Messi and his teammates celebrating an unbeaten season. In a frankly dismal campaign, it is the Galaticos' last chance at salvaging something from a season to forget.
There are only two games that really matter before a potential revamp in the summer. The Champions League final in Kiev and tonight's El Clasico and, knowing Ramos, Ronaldo and co., spoiling a Catalan party will be at the very top of their priority list.