A goal nine minutes from time by defender Yuri Berchiche took Athletic Bilbao into an all-Basque Copa del Rey final against Real Sociedad on Thursday when they edged Granada on away goals.
Athletic had led 1-0 from the first leg of the semi-final but fellow La Liga side Granada levelled the tie on the night through Carlos Fernandez in the 48th minute with a fine header from a cross by Venezuelan Darwin Machis.
Granada, in their first semi-final since 1969, then took a 2-1 overall lead thanks to a goal from German Sanchez after 76 minutes, again with Machis the provider from a corner.
However, their hopes of making the final were dashed when left-back Berchiche scored with a low drive in the 81st minute after being set up by Mikel Vesga to secure his team a spot in the April 18 finale in Seville.
With 23 titles, Athletic Bilbao are second on the all-time list of Copa del Rey winners behind Barcelona who have triumphed 30 times.
Real Sociedad ended the hopes of second division Mirandes on Wednesday with a 1-0 win which moved them into the final for the first time in 32 years.
Sociedad had already won the first leg 2-1 and they cemented their spot in the final when striker Mikel Oyarzabal scored a 41st-minute penalty after a handball in the area by a Mirandes player.
Mirandes were attempting to become the first second division club to reach the final since 1980.
Real Sociedad, who were Copa del Rey winners in 1909 and 1987 and knocked out Real Madrid 4-3 in this season's quarter-finals, will be playing in their first final since 1988 when they lost 1-0 to Barcelona.