Barcelona, who are 26-time winners of the Spanish Cup, last won the competition in 2012, while Madrid, who lost to Atletico Madrid in the final last season, have won the trophy on 18 occasions.
The two sides have already met twice in La Liga this season, with Barcelona winners on both occasions. The Catalan outfit secured a 2-1 victory over Los Blancos at the Camp Nou last October, before winning 4-3 in that famous match at the Bernabeu just last month.
It has not been plain sailing for Barcelona in recent weeks, however. They exited the quarter-finals of the Champions League to Atletico Madrid last week and enter the match off the back of a 1-0 defeat to Granada in the league at the weekend - with that loss seeing them drop to third in the table.
The current Spanish champions remain in the hunt for a domestic double, but head coach Gerardo Martino has faced huge criticism this season for a perceived change of playing style, while Lionel Messi has also drawn criticism for his lack of effort in the last few matches.
Madrid, meanwhile, secured their spot in the semi-finals of the Champions League last week despite losing 2-0 to Borussia Dortmund in Germany. Carlo Ancelotti's side were also 4-0 winners over Almeria in the league at the weekend, with that result moving them above Barcelona and into second. As it stands, they are three points behind leaders Atletico in Spain's top division.
Back-to-back defeats last month ended a long unbeaten run for Los Blancos, but the capital outfit have returned to form in recent weeks, winning four of their last five in all competitions, scoring 16 times in the process and conceding just twice.
The last time the two sides met in the final of this competition was in 2011, with that particular clash also held at the Mestalla. It was Madrid that were victorious in extra-time following a strike from Cristiano Ronaldo.
Martino is also expected to make changes in attack, with Pedro pushing for a start in a front three that is likely to include Messi and Neymar. Xavi is another that is expected to return after surprisingly sitting out the defeat to Granada at the weekend.
Madrid, meanwhile, are expected to be without the services of Ronaldo, who has a thigh injury, despite Ancelotti suggesting that his leading scorer could yet make the clash. Sami Khedira and Marcelo also remain on the sidelines, but Dani Carvajal and Xabi Alonso should return to the XI after missing the Almeria clash due to suspension.
The probable loss of Ronaldo also opens up a spot in the middle of midfield, with Asier Illarramendi expected to be preferred to the more attack-minded Isco. Angel di Maria, meanwhile, will start alongside Gareth Bale and Karim Benzema in a three-pronged attack.
Real Madrid: WWWLW
Possible starting lineups
Real Madrid: Casillas; Carvajal, Ramos, Pepe, Coentrao; Modric, Alonso, Illarra; Di Maria, Benzema, Bale
Barcelona: Pinto; Alves, Mascherano, Bartra, Alba; Busquets, Xavi, Iniesta; Neymar, Messi, Sanchez
Sports Mole says: Real Madrid on penalties