Atlético Madrid defeated Barcelona 2-0 at the Camp Nou after a red card to Pau Cubarsí shifted the momentum in the UEFA Champions League quarterfinal.Julián Álvarez and Alexander Sørloth scored for the visitors, ending a 20-year winless drought at the stadium following the dismissal of the Spanish defender.Barcelona coach Hansi Flick criticized the officiating of Istvan Kovacs and the VAR system as the team prepares for a difficult second leg.