Madrid hold the advantage as the sides prepare for the second leg of the cup semi-final at the Santiago Bernabeu.
Three weeks ago in the first leg in Barcelona, Madrid emerged from the clash with a 1-1 draw.
With the away goals rule in operation, it means a 0-0 on Wednesday night will be enough for Santiago Solari's men to advance to the final against Real Betis or Valencia and terminate Barcelona's bid for a fifth consecutive Copa del Rey trophy.
A stalemate on Sunday night in La Liga, though, could effectively end Madrid's hopes of the title.
Barcelona are nine points ahead of Real with 13 games remaining. Time still for Real or Atletico Madrid to rein in Ernesto Valverde's team. But following Barcelona's comeback at Sevilla on Saturday night, confidence will be flowing.
Lionel Messi inspired the side with his 50th hat trick for the Catalans. The Argentine, who has 25 league goals this season, also set up Luis Suarez for his first goal in six games.
An opportune moment for the Uruguayan to rediscover his marksmanship. In the first el clasico of the season on 28 October 2018, Suarez scored three times in the 5-1 annihilation of Madrid at the Camp Nou. Two days later the Madrid coach Julen Lopetegui was sacked.