It was nearly a dreadful start for the visitors when Gerard Pique looked to be the last man as he brought down Cristiano Ronaldo on the edge of the box, but the Spaniard was issued with just a yellow card.
From the resulting free kick, the Madrid skipper forced Jose Pinto into a stunning save to his right.
The hosts came close again just a few minutes later when Michael Essien's deflected cross was palmed over the crossbar by Pinto.
The away side created the first great chance of the match in the 14th minute when Andres Iniesta chipped a pass through for Jordi Alba from the edge of the penalty area, but the full-back could only slice his effort across the face of goal.
Barca came a whisker away from taking the lead just 10 minutes later as Xavi tried his luck with a free kick from the edge of the box, but his powerful effort thundered off the top of the crossbar and away to safety.
The home side had a good chance to break the deadlock with just seven minutes of the first half remaining when Jose Callejon burst down the right before firing a low cross into the box, but Pique was on hand to thump the danger clear before Ronaldo could reach it.