The young Spaniard insists his side do not fear the Liga champions after seeing the Amsterdam outfit dismantle Gerardo Martino's side in the Champions League on Tuesday
The Catalan giants have a number of their star names out through injury, and those absences told against Ajax in the Champions League on Tuesday when Gerardo Martino's men fell to a surprise 2-1 defeat in Amsterdam.
Goalkeeper Victor Valdes, full-backs Jordi Alba, Dani Alves and forward Lionel Messi will once again be sidelined for this weekend's clash, and Muniain says his team-mates will be inspired by the way the Dutch side dismantled the Camp Nou outfit.
"We have already seen that Barcelona can be beaten," The 20-year-old forward told Sport.
"Ajax showed what can be done and we have a good home record against Barca."
Athletic have lost only one of the past four encounters (three draws and one defeat) with the Blaugrana on their own turf and Muniain says he is confident of prolonging that run.
"They have important players missing in Dani Alves, Lionel Messi and Victor Valdes but we feel very comfortable and confident," he continued.
"We played very well against Malaga and if we can keep that form going, I am sure we can have a great evening."
Barca top the Primera Division on 40 points, three points ahead of nearest rivals Atletico Madrid while Athletic sit in fifth.