Pedro made a run down the right side and sent a ball in to the box that got deflected up in the air. Madrid defender Pepe over committed in the air, trying to head the ball away and left a huge hole in the middle of the defense that Lionel Messi came roaring in to like a sports car, blasting the bouncing ball past Iker Casillas to even the match at 1-1.
It certainly was not the usual majestic Barcelona build-up that we've grown accustomed due, but when your trailing by a goal and just lost your starting right back, you'll take any goals and/or momentum any way you can get them. Pepe will be shooting himself in the foot for making a poor decision to go out of position to try to play the loose ball, but emotions can often override good sense in massive derbies like this one.
Barcelona seemed settled by the goal and were able to regain control of possession in the midfield, allowing them to slow things down and end the steady stream of pressure Madrid had been pouring on for the last 20 minutes.