Two goals inside four minutes, soon after the restart, emphasised Brazil’s superiority.
Kim Min-jae was caught in possession by Estevao, who punished the mistake to make it 3-0 and the South Korea defence was breached again, when the pressing proved too much for the home side.
Casemiro fed Vincius Jnr and his expert pass provided Rodrygo with the chance to claim his second.
With 13 minutes left, Brazil eventually cleared a South Korea corner and Cunha supplied a magical through ball into the path of Vinicius Jnr, who had timed his run perfectly from his own half. There was only going to be one outcome as he calmly prodded past keeper Jo Hyeon-woo to make it five.
Cunha was withdrawn with 10 minutes to go after he had helped his side look the part at the Seoul World Cup Stadium.
