The knockout stage of the 2021 CONCACAF Gold Cup began on 24 July 2021 with the quarter-finals and ended on 1 August 2021 with the final at the Allegiant Stadium in Paradise.
In the knockout stage, if a match was level at the end of 90 minutes of normal playing time, extra time was played (two periods of 15 minutes each), where each team was allowed to make a sixth substitution.
If still tied after extra time, the match was decided by a penalty shoot-out to determine the winners.
[2] The top two placed teams from each of the four groups qualified for the knockout stage.
Man of the Match: Joaquín Rivas (El Salvador)[3] Assistant referees:[4] Michel Morales (Mexico) Henri Pupiro (Nicaragua) Fourth official: Fernando Guerrero (Mexico) Video assistant referee: Arturo Cruz (Mexico) Assistant video assistant referee: Joel Rangel (Mexico) Man of the Match: Rogelio Funes Mori (Mexico)[5] Assistant referees:[4] Caleb Wales (Trinidad and Tobago) Logan Brown (United States) Fourth official: Oshane Nation (Jamaica) Video assistant referee: Allen Chapman (United States) Assistant video assistant referee: Tatiana Guzmán (Nicaragua) Man of the Match: Stephen Eustáquio (Canada)[6] Assistant referees:[7] Frank Anderson (United States) Kathryn Nesbitt (United States) Fourth official: Armando Villarreal (United States) Video assistant referee: Bakary Gassama (Gambia) Assistant video assistant referee: Tim Ford (United States) Man of the Match: Matthew Hoppe (United States)[8] Assistant referees:[7] Alberto Morin (Mexico) Miguel Hernández (Mexico) Fourth official: Selvin Brown (Honduras) Video assistant referee: Ángel Monroy (Mexico) Assistant video assistant referee: León Barajas (Mexico) Man of the Match: Matt Turner (United States)[9] Assistant referees:[10] Juan Carlos Mora (Costa Rica) Djibril Camará (Senegal) Fourth official: Selvin Brown (Honduras) Video assistant referee: Bakary Gassama (Gambia) Assistant video assistant referee: Arturo Cruz (Mexico) Man of the Match: Héctor Herrera (Mexico)[11] Assistant referees:[10] Caleb Wales (Trinidad and Tobago) Jassett Kerr (Jamaica) Fourth official: Oshane Nation (Jamaica) Video assistant referee: Allen Chapman (United States) Assistant video assistant referee: Armando Villarreal (United States) Man of the Match: Matt Turner (United States)[12] Assistant referees:[13] Walter López (Honduras) Henri Pupiro (Nicaragua) Fourth official: Mario Escobar (Guatemala) Reserve assistant referee: Christian Ramírez (Honduras) Video assistant referee: Drew Fischer (Canada) Assistant video assistant referee: Tatiana Guzmán (Nicaragua)