An early own goal from Jordi Alba has given Real Sociedad a 1-0 lead over Barcelona at the half-time interval.
Sociedad were gifted the opening goal in just the second minute when Alba inadvertently headed into his own net while attempting to clear a dangerous cross from Sergio Canales.
Barcelona dominated possession after falling behind, and they came close to equalising when Xavi curled a free kick just over the crossbar from the edge of the box.
After surviving a penalty appeal when Inigo Martinez appeared to handle inside the box, Sociedad threatened at the other end as a Alberto de la Bella cross evaded Xabi Prieto.
A clever piece of skill from Canales almost allowed Sociedad to double their lead before the break, but Claudio Bravo responded well to make a fine save.
