Romelu Lukaku strengthened their grip on the encounter by converting from among a group of players in the box from a Daley Blind cross following a short corner.
Christian Benteke's equally stunning overhead kick had thrown Liverpool a lifeline after Daley Blind's crisp finish and Ander Herrera's penalty had put Louis van Gaal's side in control.
Manchester United recorded their fourth successive Premier League win with a dominant performance against a Sunderland side which remains in the relegation zone.
Neither side managed to impress in the shootout, but Man United edge it in the end as Casemiro hit the bar after Blind managed to give the Red Devils the lead, though the Brazilian is hardly the villain for Los Blancos who netted just one of