By Jude Summerfield After a rather emphatic embarrassment on Thursday night, Erik ten Hag and his Manchester United squad must get back on the horse for Sunday’s clash with Premier League title contenders Liverpool at Old Trafford. A poor start and a dreadful climax proved to be the Red Devils’ undoing as they slipped to a stunning 4-3 defeat to Chelsea, leaving them nine points behind fifth-place Tottenham with eight games to play. With a large group of players sidelined by injury, Ten Hag will have to mastermind a display akin to United’s FA Cup beating of the Reds last month to inject some …