Barcelona were annoyed by the referee's penalty call but there's no doubt it was the right decision. They immediately settled back into their possession-style, patiently looking to find a way through the Madrid defense. The passing was a little better, especially compared to the Milan loss, but Madrid were more than up to the task making all the right adjustments and timing their interceptions to perfection.
Basically Madrid are working their plan and outplaying Barcelona.
Madrid were also burning up Barca on the counter attack putting the home side's back line under a ton of pressure and forcing them to make quick decisions. Other than the penalty, they did a good job but Barca are definitely playing with fire at the back.
The only new chance that Barcelona were able to generate after penalty was a shot from distance by Andres Iniesta that went wide, much like his earlier effort.