Javier Mascherano said Barcelona cannot be written off to add a record 12th Supercopa de Espana to their trophy cabinet, despite losing the first leg 4-0 to Athletic Bilbao on Friday.
Aritz Aduriz's hat-trick complemented Mikel San Jose's long-range opener, adding further evidence to the argument Luis Enrique's side have considerable defensive frailties.
But Mascherano said Barca can turn around their form - they have shipped eight goals in two games - at Camp Nou on Monday.
"Do not give us up for dead. We can still come back and win the trophy," the 31-year-old said.
"It is a party in our house. We won a lot of games by big margins. It will be a tough game because the opponent is strong but we have the choice at home.
"It was a timely circumstance. They had three or four chances and made four goals."
The Argentine said Barca's attacking shortcomings were not down to creativity, but polish.
"We had some scoring chances," he said.
"It is correct our touches were what went wrong. But above all, we have faith to return."
Second-half substitute Andres Iniesta, who was introduced just prior to the first of Aduriz's three goals, said it was simply a bigger challenge for his team-mates to overcome.
"In the next game we will have to try to turn the tie and get it right," the midfielder said.
"There is no margin of error and the challenge of winning the Supercopa is even greater."
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