In Sunday's match against their arch-rivals, the Blaugrana are relying on a symbol of Catalan nationalism.

The Clasico on Sunday will be played in new colours, as Real Madrid and Barcelona have exchanged their customary colours for new ones in the showpiece match.
Madrid wore a black shirt, whereas Barcelona wore a yellow jersey with the iconic Senyera, a symbol of the Catalan area.

But what does the Senyera symbolise to Barcelona, and why has their uniform been changed for this match? 
Against Real Madrid, why is Barcelona wearing a yellow Senyera kit?

According to club insiders, president Joan Laporta is to blame for the shirt change since he wanted Barca to play in the traditional Catalan colours.

It's a step up from the club's appearance in last year's Clasico at the Estadio Alfredo Di Stefano, when they wore a shirt with their customary blue and red but also with the flag's red lines going down it, which they also wore in a game versus Atletico Madrid.
What exactly is a Senyera?
The Senyera is one of Europe's oldest flags that is still in use today, dating back to approximately the end of the first millennium.

According to mythology, it all started with the death of Count of Barcelona Guifre el Pilos (Wilfred the Hairy) in an 897 battle between French and Norman armies.
In honour of the late count's assistance in the battle, the French emperor Louis dipped four fingers in Guifre's blood and etched four lines on his copper shield, establishing Catalunya's flag and coat of arms.