I'd go full strength bar a couple of experiments at the weekend and hopefully we can start to put together a bit of a cup run. I'd throw Lukaku straight in to see what he can offer and I'd give Schar another run out in midfield. He did well at CM against Blackburn but this will be a tougher test. I'd try Ritchie in the Atsu floaty midfield role as well since we have an actually LWB now. Be intresting to see if it works.
Fernandez Lascelles Lejeune
Yedlin Schar Longstaff Ritchie Lukaku
If that does work then I'd make a load of changes against City. Clark, Joselu, Hayden, Atsu, Murphy, Manquillo, Sterry etc all in for a run out and to rest our key players. Then I'd revert back to the team above against Spurs.