Barcelona and Real Madrid will look to avoid any slip-ups with Atletico Madrid on a winning run.
Inaki Williams scored twice as Athletic Bilbao won 2-0 at Fenerbahce on Wednesday to climb top of the Europa League standings.
Kylian Mbappe said he will take full responsibility for a "big mistake" after the striker missed another penalty in champions Real Madrid's 2-1 defeat at Athletic Bilbao in La Liga on Wednesday.
Athletic Bilbao vs Real Madrid Live Streaming LaLiga Live Telecast: Los Leones have failed to beat Real Madrid in each of their last 18 games in LaLiga, losing 15 and drawing three times during the same course.
Athletic Bilbao cruised to a 3-0 win over Elfsborg on Thursday to move level on points with Lazio at the top of the Europa League table, while Chelsea made it four wins from four in the Conference League.
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