Barcelona's hopes for a remarkable comeback were not to be as Athletic Bilbao managed a 1-1 draw to win the Spanish Super Cup 5-1 on aggregate.
Athletic's shock 4-0 win in Friday's first leg had given the Basque club a comfortable advantage, but Luis Enrique's men remained confident they could turn it around at Camp Nou on Monday.
But despite Lionel Messi's opening goal before half-time, a red card to Gerard Pique put the comeback in doubt and Aritz Aduriz's close-range finish sealed a famous result for Athletic.
Luis Enrique switched goalkeepers after Marc-Andre ter Stegen conceded eight goals in his last two outings, opting for Claudio Bravo. The manager also returned to his first-choice squad -- except for Neymar, who is out with mumps and the injured Jordi Alba -- after Bilbao picked apart his mix of regulars and reserves in the first leg.
Needing at least four goals to force extra time, Barcelona pushed hard from the beginning, and Pique nearly scored in the seventh minute when he hit the crossbar.
Messi found the breakthrough two minutes before the break when he chested down a pass from Luis Suarez and scored from close range.
In the 55th minute, Pique thought Aduriz should have been ruled offside, and though the attack came to nothing he was shown a red card after arguing with the linesman.
Aduriz, who scored a hat trick in the first leg, then put the outcome beyond doubt when he scored in the 74th minute, and not even Kike Sola's 86th minute dismissal for a dangerous tackle could damper Athletic's party.
Bilbao ended a 31-year trophy drought. Their last title came in 1984, when they beat Barcelona 1-0 in the Copa del Rey final to complete a double of cup and league trophies.
The result means Barcelona can't match the six titles they won in a single calendar year under Pep Guardiola in 2009.
Last week, Barcelona won the UEFA Super Cup after completing a rare treble of the Champions League, La Liga and Copa del Rey last season, and they will play in the Club World Cup in December.