Barcelona boss Luis Enrique has insisted his side can pull off a monumental fightback on Monday to add the Spanish Super Cup to their 2015 trophy haul despite trailing Athletic Bilbao 4-0 heading into the second leg.

An under-strength Barca side was blown away by the Basques on Friday as they exacted revenge for defeat in May's Copa del Rey final at the Camp Nou thanks to Aritz Aduriz's hat-trick and a spectacular opener from just inside the Barca half by Mikel San Jose.

However, a defiant Enrique insisted a goal-laden squad spearheaded by Lionel Messi and Luis Suarez is capable of turning the tie around.

"We are completely convinced that if we do things well we will have a chance," Enrique said on Sunday.

"There is no doubt we will try to do it. I have looked at the statistics and last season we scored four or more goals in 18 games.

"When Barca play well anything can happen."

It was the first time Barca had lost by four goals against Spanish opposition for eight years and the first time in 14 years they had conceded four times in two consecutive matches.

The European champions had beaten Sevilla 5-4 after extra time in energy-sapping conditions in the Georgian capital Tbilisi to win the UEFA Super Cup just three days prior to their trip to Bilbao.

Enrique had left out the likes of Gerard Pique, Sergio Busquets, Ivan Rakitic and Andres Iniesta from the start at San Mames as a result.

Yet, they will be back close to full-strength for the return with only the ill Neymar and injured Jordi Alba missing out.

"After the result you are down because no one expected it. Even though we didn't play well the difference in the scoreline was exaggerated," said defender Javier Mascherano.

"We need to be convinced that we can do it. The difficulty is huge, the result isn't an easy one but it is an important challenge for us. No one has ever done it in a Spanish Super Cup.

"If we play well we will score goals. Hopefully, we can get enough to turn the tie around.

"The most important thing in these type of games is the mental aspect. The team is well prepared in this sense. The desire to win another title makes you forget the first leg.

"We all believe the possibility exists to comeback. Obviously it is a final and the opponent will be prepared, but we know we have to team capable of doing it."

Barca believe history could also be on their side. A Messi hat-trick sparked a 4-0 win over Sevilla in the 2010 Super Cup after a similarly weakened side had lost the first leg 3-1.

Athletic's first-leg performance was all the more impressive as they are also missing four first-team regulars through injury.

Inaki Williams, Ander Iturraspe, Mikel Rico and Iker Muniain are all expected to miss out once more and Aduriz remains cautious.

"We cannot think that Barca in their stadium can't score four goals. They are the best and capable of doing anything."

Victory would end a 31-year barren run without a trophy for Athletic and would be particularly sweet after they lost the Copa del Rey final to Barca in three of the past seven years as well as the Super Cup in 2009.

"If we lift the Cup it will be the best night of my career," added Aduriz.