The home side dominated proceedings in the first period and took the lead late in the half through Sergio Busquets.
Moments later, it got worse for the visitors as Inigo Martinez was handed a red card for dissent.
Barcelona, who dominated from that point forward, were 2-0 ahead on the hour mark when Gorka Elustondo fired into the back of his own goalkeeper inside the box, with Enaut Zubikarai credited with the own goal.
Here, Sports Mole dissects the 90 minutes of action between the two La Liga rivals.
On target: 7
On target: 2
Was the result fair?
In truth, Barcelona should have put this tie to bed this evening. The Catalan outfit were fortunate with a couple of decisions from the referee, but they were the better side from start to finish. Lionel Messi had a number of golden opportunities for the Catalan outfit, but could not find the back of the net despite his best efforts. That said, Sociedad had their moments and twice forced smart saves from Jose Pinto in the Barcelona goal.
In a half-empty Camp Nou, Barcelona returned to winning ways this evening. However, there is still something not quite right with the Spanish champions. They dominated possession and indeed created a number of opportunities, but too often their final pass was wayward. It mattered little in this particular match, but it will be a worry for head coach Gerardo Martino against better opposition. There were also a few uncomfortable moments defensively, but that said, Barca are on the verge of another final ahead of the second leg next week.
It was a surprise not to see skipper Xabi Prieto, along with a couple of others, in the Sociedad XI this evening. However, under the circumstances, the Basque outfit can be pleased with their performance at the Camp Nou. Despite relinquishing possession, they had their moments in the first period and might have scored an away goal but for some smart goalkeeping from Pinto. In the second half, it was a case of defend, defend, defend and with just a two-goal deficit, they are still in with a chance of turning the tie around at San Sebastian next week.
Sports Mole's man of the match
Sergio Busquets: The clash at the Camp Nou did not have too many standout performers, but Busquets was the pick of the bunch this evening. The Spaniard was his usual calm and composed self in possession of the ball, while he provided a constant shield in front of his back four. The midfielder also grabbed himself a rare goal with a smart finish in the latter stages of the first period.
Sociedad should have had a penalty in the latter stages of the first period when Carlos Vela was brought to the ground by Javier Mascherano inside the Barcelona box, but the referee was not interested. Moments later, Sociedad were 1-0 behind and down to 10 men. Such a decision could have changed the course of this tie. That said, Elustondo's decision to fire into the back of his own goalkeeper for Barcelona's second should also be considered for this particular award. It was an incredible gaffe from the Spanish midfielder.
It was a relatively quiet first period for Jose Gonzalez until the latter stages of the half. Within the space of two minutes, the Spaniard had turned down a clear penalty appeal for Sociedad and sent Martinez from the field - decisions that will be contested by Sociedad. However, it was more straightforward in the second period with Barcelona in control of the possession for long spells.
Barcelona: The Catalan outfit will attempt to return to winning ways in La Liga when they travel to Sevilla on Sunday evening.
Sociedad: Sociedad are also in action on Sunday and will attempt to keep their top-four challenge on course with victory at home to Levante.