In the 83rd minute, 19-year-old Roony Bardghji was substituted for Pau Cubarsí at the Santiago Bernabéu stadium in Madrid.
Not since Zlatan Ibrahimovic in the autumn of 2009 decided his first and only El Clásico, at Camp Nou, has a Swede been involved when the two Spanish football giants meet.
Barcelona were chasing an equalizer when Bardghji entered the pitch. But Real Madrid held on to a win that means "Los Blancos" now have five points down to second-placed Barça in La Liga.
Much was about Kylian Mbappé and Jude Bellingham. Mbappé had a dream goal ruled out early after a VAR check, but then scored 1-0 in the 22nd minute after beautiful preparatory work by Bellingham.
Fermín López equalized in the 38th minute, but the draw only lasted for five minutes before Bellingham pushed in 2-1 for Real Madrid from close range.
It also became the winning goal.
In the second half, Mbappé had the opportunity to extend the lead from eleven meters, but Wojciech Szczęsny saved the Frenchman's penalty.
