Athletic Bilbao eliminated Real Madrid from the Copa del Rey with an 89th-minute goal from Alex Berenguer.
Berenguer cut inside and hammered a crisp finish into the far corner with time running out to startle Carlo Ancelotti’s troops.
Bilbao will be seeking a third consecutive season in the final.
They became only the second side, after Real Zaragoza, to knock out both Real Madrid and Barcelona in the same season.
Real’s defeat puts an end to their domestic double chances, as the club currently sit atop La Liga, four points clear of Sevilla.
Valencia, Real Betis, and Rayo Vallecano have all advanced to the cup’s final four.