Barcelona will take a slender advantage to Camp Nou after they beat Real Madrid 1-0 in their Copa del Rey semifinal first leg at the Santiago Bernabeu on Thursday.
An Eder Militao own goal was all that separated the two Spanish giants, with Carlo Ancelotti's men having a lot of the ball but unable to craft much in the way of chances.
Militao's own goal was only the fourth this century in a Clasico, three of which have favored Barca after Ivan Helguera's in May 2002 and Raphael Varane's in February 2019.
Madrid may consider themselves fortunate not to lose by more, however, with Ansu Fati inadvertently denying team-mate Franck Kessie a certain goal in a second half largely dominated by the hosts.
Karim Benzema had the ball in the net early on when he chested down a cross from Vinicius Junior and volleyed home, only to be flagged offside.
Despite Madrid dominating early on, it was Barcelona who took the lead in the 26th minute.
Ferran Torres played in Kessie, whose shot went in off Militao after Thibaut Courtois had initially saved from the Barca midfielder.
Vinicius saw an effort blocked by Ronald Araujo early in the second half, while the visitors should have doubled their lead 18 minutes from time.
Kessie met Torres' cut-back but saw his goal-bound shot deflected wide by substitute Fati with Courtois stranded.
Nevertheless, Xavi's men held on despite Madrid's desperate late onslaught.