Well, things are really interesting at the Camp Nou now. Karim Benzema, on as a substitute for the disappointing Gonzalo Higuain, has just justified the switch and brought the match back to level terms after a brilliant piece of attacking play. Barcelona have looked vulnerable at the back all evening and Real Madrid had been unable to take advantage, but a goal by Cristiano Ronaldo got things going and now we've got our second.
Xabi Alonso headed a clearance back towards Barcelona's goal and Benzema managed to beat Carles Puyol to the ball, left him in the dust with a clever turn, and then while falling over backwards, slipped the ball past Jose Pinto and into the back of the net. So it's 2-2 now, and 4-3 Barcelona on aggregate. If Madrid can find another goal, they're through. Wow.
For more on the two teams, check out Real Madrid blog Managing Madrid and FC Barcelona blog Barca Blaugranes. We have live coverage of the match in our Real Madrid vs. Barcelona, 2012 El Clasico StoryStream.