It's an uphill battle for Los Blancos, but the comeback kings will give it a chance. They need to win by three goals to force extra time, while a four-goal win or better will see them through to the last four. Scoring early will be pivitol, but even a two-goal victory won't be enough.

Enjoy Wednesday's UEFA Champions League quarterfinal action as Barcelona took on Borussia Dortmund and Paris Saint-Germain took on Aston Villa.

In Wednesday's other quarterfinal first leg, Paris Saint-Germain overcame a 1-0 deficit to English Premier League club Aston Villa at the Parc des Princes en route to a 2-1 victory. The decisive rematches will be played next week in Dortmund and Birmingham, respectively. Here are three quick takeaways following Wednesday's games.