Athletic Bilbao roared to a stunning 4-0 victory over Barcelona in the first leg of the Spanish Super Cup after striker Aritz Aduriz picked apart the European champions with a second-half hat trick on Friday.
It was Barcelona's biggest loss under coach Luis Enrique, whose decision to start several reserve players helped the Basque hosts focus on keeping Lionel Messi in check.
Before Aduriz turned it into a rout, Mikel San Jose set the tone in the 13th minute by lobbing Marc-Andre ter Stegen's long clearance back over the goalkeeper's head with a shot from inside the center circle.
Barcelona will have to rebound on Monday at Camp Nou to keep alive its quest to repeat the six titles in one year won in former coach Pep Guardiola's first season.
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