A first-half penalty earned Real Sociedad a 1-0 win at second division side Mirandes on Wednesday and a 3-1 aggregate victory that sent them through to the Copa del Rey final.
Real Sociedad, who won the first leg 2-1 at home, will face either Granada or Athletic Bilbao on April 18 (stream all matches live on ESPN+). Athletic Bilbao won the first leg 1-0 at home.
Sociedad went ahead five minutes before the break when Mikel Oyarzabal converted a penalty following a Mickael Marsal hand ball in the area.
They went close to doubling the tally when Adnan Januzaj hit the woodwork one minute into the second half.
Mirandes, who had only one shot on target in the match, never threatened to continue their dream run in the competition, during which they eliminated La Liga sides Villarreal and Sevilla.
It's the first Copa del Rey final for Real Sociedad since 1988 when they lost to Barcelona.