If Matip is fit, the team picks itself. Without Matip, we need to accept that we will concede chances whoever we pick at CB, so personally, I think we should go with Williams as he offers more with the ball. We're likely to be up against Rashford and Cavani, which is not dissimilar to Harry Kane and Son, and Williams/Fabinho handled them ok for the most part.
But more importantly for me, attack will be the best form of defence and as we can finally get Fabinho, Trent, Robbo, Gini, Hendo, Thiago, Mane, Salah and Bobby all on the same pitch after a good weeks training at the new training centre, that should be far too much for them. 3-1.