Stanley N'Soki plays leftback and centreback, is young and pretty highly regarded. He'd be a good shout.
One thing I love about this team is that there are so many lovable players on it. I want to say Robertson is my favourite player, but I could say the same about van Dijk, Mane or Firmino as well. Wijnaldum, Milner, Alisson, Trent, Henderson, Salah etc. are also all so likeable...what a time to be a Red.