The away side entered the break with a one-goal lead courtesy of an early strike from Chilean winger Alexis Sanchez.
The lead was 2-0 in the early stages of the second half when Cesc Fabregas found the back of the net from outside the box, before the Spanish international added his second moments later.
Read how it all unfolded in Sports Mole's minute-by-minute live commentary of the action below.
CELTA VIGO: Yoel; Mallo, Cabral, Fontas, Aurtenetxe; Oubina, Alex Lopez; Rafinha, Augusto, Nolito; Charles
BARCELONA: Valdes; Alves, Puyol, Bartra, Adriano; Fabregas, Song, Busquets; Pedro, Sanchez, Messi