After an Eric Garcia own goal sent Diego Simeone's side ahead early on, Antoine Griezmann, Ademola Lookman and Julian Alvarez struck to give Atletico a landslide lead by half-time.

Barca defender Garcia was sent off in the final stages, with Atletico maintaining their significant advantage on the record 32-time winners, which they will take into the second leg at Camp Nou on March 3.

Both sides missed good chances in the second half, with Barca's Pau Cubarsi having a goal disallowed before Garcia was sent off in the final stages.

Atletico were able to preserve their significant advantage on the record 32-time winners, which they will take into the second leg at Camp Nou on March 3.

Well off the pace in La Liga and not showing the quality of a side likely to go deep in the Champions League, the Copa del Rey represents Atletico's best chance of silverware this season.

With that motivation in mind, the Rojiblancos conjured the best football of their season to completely dismantle the Spanish champions in the first half.

The hosts took the lead after seven minutes when Garcia's pass, on the uneven Metropolitano stadium pitch, bobbled towards Joan Garcia and then under the goalkeeper's foot.

The Barca stopper ran back towards his goal to try and save it but the ball crossed the line first, with Lookman ramming it back into the net for good measure, although it was recorded as an Eric Garcia own goal.

Former Barca striker Griezmann slid home the second as Atletico breached the Catalans' high defensive line repeatedly, leaning on the pace of Giuliano Simeone and Lookman.

Fermin Lopez hit the crossbar for Barcelona but it was one-way traffic and Atletico nearly got a third when Alvarez's effort was cleared off the line by Jules Kounde.

Eventually Nigeria international Lookman steered home the third at the end of a fine team move, with overjoyed Atletico coach Simeone racing down the touchline in celebration.

- Alvarez drought ends -

Having spent much of the season demanding his team take their chances more clinically, all of the Argentine's dreams came true at once.

Alvarez, who had failed to score in his last 11 matches, ended his drought for Atletico's fourth, ramming home from just inside the area.

Atletico goalkeeper Juan Musso saved well from Lopez to keep his clean sheet at the interval.

Barcelona thought they had pulled one back in the second half when Pau Cubarsi netted but it was controversially disallowed after a long VAR review for offside.

With a few minutes remaining the league leaders' night got even worse, when Eric Garcia was sent off for a foul on Alex Baena as he ran through.

Ferran Torres's poor pass sold his team-mate short and he clumsily felled the Atletico playmaker.

Alexander Sorloth and Torres spurned further chances at each end as the game kept its frantic pace until the end.

On Wednesday Real Sociedad beat Athletic Bilbao 1-0 in the first leg of the other semi-final clash.