Amorim would like United to build up with a genuine three at the back, rather than the four it has been when protection is the first priority. At Anfield, United took the lead because Martinez sensed a moment to press high, snapping into Mohamed Salah to win the ball and then stay up to receive Fernandes’ slipped pass.

Manchester United are reportedly keen on bolstering their defensive options with the signing of Barcelona's Andreas Christensen. The Danish international has struggled for regular first-team football at the Camp Nou and could be available for a move away from Catalonia.