The visiting Scottish fans were all set to cheer a well earned point at Barca's Nou Camp fortress but instead they were left crestfallen after conceding a goal in the 93rd minute with Alba bundling the ball over from close range.

Barca, who lead the group with nine points, have not been beaten at home for three years in Europe but they went behind when a header from Giorgos Samaras deflected off Javier Mascherano after 16 minutes.