Do Man Utd need to sign a centre-back?

[BBC]So far, Manchester United have signed a back-up goalkeeper, two midfielders and a young forward this summer, but former Red Devils defender Danny Simpson says they need fresh blood in another position."Lisandro Martinez is injured, Matthijs de Ligt gets injured a lot and Harry Maguire is 33 now, so I think we could do with a centre-back," Simpson told BBC Radio Manchester.United currently have a wealth of experience in the centre-back department with Martinez, De Ligt and Maguire, but injur