Five minutes later it was 2-0 with a Neymar penalty and Richarlison added a brilliant third after a spell of juggling then a razor combination with Marquinhos and Thiago Silva that had Brazil's delirious fans dancing and neutrals everywhere purring.
Lucas Paqueta volleyed in the fourth after 36 minutes and the five-times champions played the second half as an exhibition, denied more goals only by impressive Korean goalkeeper Kim Seung-gyu, as they turned their attention to Friday's quarter-final meeting with Croatia.
Korea worked tirelessly and bravely to try to limit the damage and were rewarded for their own attacking efforts when Paik Seung-ho smashed in a brilliant long-range shot beyond Alisson 13 minutes from time.