An early own goal by Eric Garcia set the tone for Diego Simeone’s side before Antoine Griezmann, Ademola Lookman and Julian Alvarez all found the net in a ruthless opening 45 minutes at the Metropolitano Stadium.
The hosts struck after just seven minutes when Garcia’s misplaced pass, slowed by the uneven surface, slipped under goalkeeper Joan Garcia’s foot and rolled into the net. Lookman forced the ball home to ensure the finish, though the goal was officially recorded as an own goal.
Atlético repeatedly exposed Barcelona’s high defensive line, with Griezmann sliding in the second after a swift attacking move. Despite a crossbar effort from Fermin Lopez and a goal-line clearance by Jules Kounde to deny Alvarez, it was largely one-way traffic before the break.
Lookman added the third, calmly steering home at the end of a flowing team move that prompted jubilant celebrations from Simeone on the touchline. Alvarez then ended an 11-match goal drought by firing in Atlético’s fourth from just inside the area, capping a dominant first-half display.
Barcelona attempted a response after the interval and thought they had reduced the deficit when Pau Cubarsi found the net, but the effort was ruled out following a lengthy VAR review for offside. Matters worsened for the Catalan side late on when Eric Garcia was sent off for a foul on Alex Baena as he raced through on goal, compounding a difficult night for the visitors.
Both sides created further chances in a frenetic second half, with Alexander Sorloth and Ferran Torres unable to convert opportunities at either end. Atlético goalkeeper Juan Musso also produced key saves to preserve the clean sheet.
With the second leg scheduled for March 3 at Camp Nou, Atlético carry a significant advantage over the record 32-time Copa del Rey winners. Given their struggles to keep pace in La Liga and doubts over a deep Champions League run, the domestic cup now represents their most realistic path to silverware this season.
In the other semi-final first leg on Wednesday, Real Sociedad edged Athletic Bilbao 1-0.