A magnificent goal from Leo Messi after 27 minutes, his fifth of the competition, was the key moment of the game, reported Xinhua. (Agencies)
Messi received the ball well just inside the Real Sociedad half, before embarking on a trademark solo run and beating home goalkeeper, Enaut Zubikaria.
After Barca's 2-1 win in the first leg a week ago, Messi's goal meant that Real Sociedad would need to score four times in order to reach the final.
Despite the task that faced them, Real Sociedad showed themselves willing to do everything in their power from the start.
Cheered on by the fans in a packed Anoeta Stadium, Real Sociedad looked to take the game to Barca, but found themselves against the best version of Barca, which looked to control the ball and frustrate their rivals, while always working to provoke a space in the rival defence.
Carlos Vela was again a threat for Real Sociedad but was denied an equalizer 10 minutes from halftime by Dani Alves after his shot had beaten Barca keeper, Jose Pinto.
Barca will play Real Madrid in the final after two Cristiano Ronaldo penalties gave Real Madrid a 2-0 win on the night and a 5-0 triumph on aggregate in a non-event of a return leg against Atletico Madrid on Tuesday.
A magnificent goal from Leo Messi after 27 minutes, his fifth of the competition, was the key moment of the game, reported Xinhua.