Javier Mascherano has called on Barcelona's supporters to turn out in force to help them overturn a four-goal deficit in the second leg of the Supercopa de Espana.

Luis Enrique's treble winners were given a rude awakening in the first meeting with Athletic Bilbao on Friday as they were humbled 4-0 at San Mames - Aritz Aduriz grabbing a hat-trick.

Mascherano - one of Barca's four captains for the 2015-16 campaign - remains confident they can turn the final around at Camp Nou, though, and says the fans have a huge part to play.

"The fans have to play the same role as in recent years," said the Argentina international. "In big matches they have always been behind us and they have helped us to plenty of important wins.

"We have had games at home where the fans have been the number 12.

"We have to show to the fans from the first minute that we can come back. If they see that then they will get behind us."