Pau Cubarsi red card vs. Atletico Madrid, explained: Why Barcelona defender was sent off after VAR review

Barcelona's Champions League quarterfinal first leg on Wednesday was the second of three games they have with Atletico Madrid in early April.

The Catalans won 2-1 in La Liga last weekend and now face Diego Simeone's side, who eliminated them from the Copa del Rey this season, in a two-legged European matchup.

The first leg at Camp Nou swung the way of Atletico in the first half when Pau Cubarsi was shown a straight red card for a foul on Giuliano Simeone.

Referee Istvan Kovacs initially showed a yellow card but upgraded it to a red after a VAR review.

MORE: Full commentary and highlights from Barcelona vs. Atletico Madrid

Pau Cubarsi red card vs. Atletico Madrid, explained

In the 41st minute of the game, Cubarsi was penalised for a foul on Simeone around 25 yards from the Barcelona goal.

Julian Alvarez played a terrific pass in behind the Barca defence and, as Simeone ran onto the ball, Cubarsi collided with his rear leg and sent him sprawling to the turf.

Referee Kovacs awarded a free-kick and issued a yellow card to Cubarsi, but after VAR looked back at the incident, they recommended an on-field review from the match official. Kovacs watched the footage carefully before deciding that Cubarsi's punishment should be upgraded to a red card.

As Cubarsi was the last covering defender, and Simeone would have been clean through on goal — through the centre of the box — if he had not been prevented from getting to the ball, the referee and VAR appeared in agreement that Cubarsi's foul constituted the denial of a clear goal-scoring opportunity.

To make matters worse for Barca, Alvarez then scored directly from the free-kick.