You have to go to the strip. It's where loads of the local fans go for their pregame drinking – try hitting up la Travessera de les Corts, just off the L3 Green metro line. It's fan-city over there since there is a good selection of sports bars (or bars with sports on the TV, at least), varied and delicious options in terms of local beers and, of course, a range of slightly expensive but very edible pre-match food.

Palau Blau Grana is located in the center of Barcelona. Only few steps from there you can find many cool bars like Futballarium Barcelona. I especially like this one and here you can order nice hamburgers with cold beer. You will love the decoration! For nice atmosphere and "tapas", I suggest to go to Taller de Tapas. It is a big bar and prices are not very high. Before going to the venue, it's a good choice!