Real Sociedad started the game well with Mexican forward Carlos Vela causing Barca's defensive partnership of Gerard Pique and Javier Mascherano all sorts of problems and it was the former Arsenal man who almost gave the visitors a shock early lead but he was denied by excellent goalkeeping from Jose Pinto.

Moments later and Vela would provide for Antoine Griezmann but he was also denied by Pinto and that chance then seemed to wake Tata Martino's side and they dominated the game from then on.

The Catalans' first real chance came when Dani Alves worked hard down the right hand side and supplied Cesc Fabregas but the midfielder could only send his effort just wide.

Jordi Alba then created from the left but more good goalkeeping, this time from Sociedad's Zubikarai denied Lionel Messi on two occasions.

The four time Ballon d'Or winner then came close from a costless-kick, crashing his effort on to the woodwork.

Carlos Vela then caused more problems as he broke costless from Barca's defence but Mascherano did all he could to deny the striker room for a shot.

Sociedad appealed for a penalty and they felt even more aggreived when Sergio Busquets tapped in from close range from the following counter attack.

Then a moment of madness as Inigo Martinez was shown a straight red card for protesting.

The second half was more of the same as Xavi Hernandez and Lionel Messi dictated the pace of the game, creating plenty of chances to go 2-0 ahead.

But, the second goal would come in strange circumstances as Zubikarai denied Alexis Sanchez but then saw Carlos Martinez's clearance hit him and go in to the back of the net.

Barca looked the extend the lead even more with Pedro Rodriguez coming close on the 70th minute mark but his volley went just over the crossbar.

Substitute Andres Iniesta also came close but again his effort was over the bar as Barca kept increasing the number of efforts on goal.

Perhaps the best chance for Barca to extend that lead came when Messi got on the end of a superb team move but Zubikarai managed to deny the Argentine forward.

Sociedad did hold on in the end but it will be Barca who are the happier of the two teams heading in to next week's second leg.