Two goals in the first half and one in the second replicated the demolition of Partizan Belgrade in the Europa League last Thursday night.
Andreas Pereira's opener and an own goal from Brighton’s Davy Propper once more made it a comfortable watch for United fans as Ole Gunnar Solskjaer's men dominated the first half.
Lewis Dunk wrecked the clean-sheet target when he pulled a goal back for the visitors after the break but it failed to derail the Reds, who immediately gained a grip back on the game when Marcus Rashford thundered in a belter two minutes after the Brighton response.