Cadiz booked a semi-final spot against fierce rivals Sevilla after a 1-1 draw in Bilbao completed a 4-3 aggregate victory.
Both teams sprung surprises in attack; Bilbao included youngster Fernando Llorente, with no place in the starting line-up for either Urzaiz or Etxeberria, while Cadiz handed a first start of the season to 20 year old Manuel de Gomar.
Bilbao needed to overturn a 3-2 first leg deficit and with Cadiz more than willing to attack in search of away goals themselves, it led to an open game.
Cadiz took a commanding 4-2 aggregate lead with a goal in first half injury time. De Gomar, who had looked lively, set it up, winning possession and bursting into the box. When his route to goal was cut off, the youngster kept his composure to find strike partner Mirosavljevic, who finish low past Aranzubia.
Needing two goals to go through, Bilbao brought on Etxeberria soon after half time. He was soon causing problems and had a couple of half chances. Cadiz were defending strongly and relying on breaks. Two such breaks brought great chances for Mirosavljevic, who had his shot well saved, and de Gomar who should perhaps have done better than shooting wide when through on goal.
Bilbao eventually made their possession pay. Yeste, who had been lively all night, did brilliantly on the left to get away from his marker. His low near post cross was met first time by Etxeberria and a tense last 20 minutes was ensured.
Bilbao kept attacking and changed things, going with 3 up-front. Cadiz responded by sacrificing a striker for an extra center back. With just over 5 minutes to go, Oli could have ensured a comfortable finish as he got on the end of a long freekick and took the ball round Aranzubia. With a slight angle and off balance the striker could only shoot wide of the open goal though. Bilbao tried to launch a grandstand finish but Cadiz held tight and celebrated wildly at the final whistle.