The Reds announced on Sunday that a deal has been completed for the Colombia international to join the club from FC Porto on a long-term contract.
And Diaz has already selected a shirt number ahead of his forthcoming arrival on Merseyside, with the attacker taking the vacant No.23.
Previous wearers of the No.23 for Liverpool include Emre Can, Jamie Carragher, Robbie Fowler and, most recently, Xherdan Shaqiri.