Robert Lewandowski shrugged off a string of missed opportunities to earn Barcelona a 2-1 win over Athletic Bilbao on Saturday in La Liga.
Athletic Bilbao forward Nico Williams said he was racially abused by "stupid people" during his team's 3-1 defeat at Atletico Madrid on Saturday in La Liga.
Athletic Bilbao arrive in the capital knowing a victory would give them a huge chance of returning to Europe's premier competition for the first time since 2014.
Ernesto Valverde's Athletic, defeated in their six previous appearances in the final, brought an era of almosts to a close with a hard-fought win.
Rodrygo fired La Liga leaders Real Madrid to a 2-0 win over Athletic Bilbao with a superb brace on Sunday to restore their eight-point advantage on Barcelona.
Real Madrid have a comfortable eight-point lead on champions Barcelona with nine matches remaining.
First half goals from brothers Inaki and Nico Williams sent Athletic Bilbao on their way to a 3-0 win -- 4-0 on aggregate -- over Atletico Madrid on Thursday and into the Copa del Rey final.
Girona's unlikely La Liga title bid suffered another dent in a 3-2 defeat by Athletic Bilbao on Monday, with Alex Berenguer striking twice for the Basque side.
Real Madrid have the division's best defence, conceding just 15 goals in 23 league games, while Girona boast the best attack, with 52 goals.
Athletic Bilbao have lost the last six Copa finals they have played in, although with 23 triumphs have won more than any side except Barcelona.
Athletic Bilbao kept up the pressure on La Liga's top four with a thumping 4-0 win over Mallorca on Friday.
Inaki Williams raced back from Africa to face Barcelona in the Copa del Rey and sent Athletic Bilbao into the semi-finals by scoring a crucial goal in their 4-2 extra-time triumph on Wednesday
Ernesto Valverde's impressive Athletic Bilbao beat Sevilla 2-0 on Thursday to move provisionally third in La Liga, ahead of Atletico Madrid and Barcelona
Atletico fell 2-0 at Athletic Bilbao earlier Saturday but Barcelona could not take full advantage in an entertaining clash on the east coast
Athletic Bilbao moved to fifth in the La Liga table with a 1-1 draw at Granada on Monday in a game restarted from Saturday after a fan died at the stadium
Players from both sides left the pitch 20 minutes after play was suspended, with supporters then requested to leave the stadium after the decision was eventually taken to abandon the game.
Surprise package Girona failed to return to the top of La Liga on Monday after they were held 1-1 draw at home by Athletic Bilbao.
Teenage debutant Marc Guiu snatched champions Barcelona a 1-0 win over Athletic Bilbao just seconds after coming on from the bench on Sunday in La Liga