Liverpool delivered the complete performance and Mohamed Salah became the club's record Premier League goalscorer as Manchester United were overwhelmed at a joyous Anfield.
United's renaissance under manager Erik ten Hag already has the tangible reward of the Carabao Cup but Liverpool unleashed a brutal reality check on their progress with a severe thrashing.
Liverpool took control of what had been a tight game, with Bruno Fernandes and Marcus Rashford missing presentable chances, when former Old Trafford target Cody Gakpo applied a smooth finish to Andy Robertson's perfect pass two minutes before the break.
The second half was a tale of sheer joy for Liverpool and unrelenting misery for United, starting after 47 minutes when Darwin Nunez's header diverted Harvey Elliott's driven cross past goalkeeper David de Gea.