3 options for the back 4. He could pair walker and gvardiol at cb to get his most senior centre half partnership and push the youngsters out wide so we see from right to left, Lewis, walker, gvardiol, Simpson-pusey. probably the most unlikely but wouldn't rule it out.
2nd option is Lewis, walker, Simpson-Pusey, gvardiol. This way sees players move the least.
The last option and my preferred one would be walker, Simpson-pusey, gvardiol, Lewis. This keeps Simpson-pusey in his most comfortable position and flanks him with our most senior defenders. Lewis isn't going to be in his position most of the game anyway and with him left back, Nunes on the left wing is by far the most likely of our advanced players to be able to get back in and cover the gaping holes left.
This makes the most sense to me. We shall find out soon enough. Either way it's a horror show waiting to happen.