Kenny - Keane - Jagielka - Baines
Mirallas - Gueye - Schneiderlin - Sig
Calvert Lewin - Sandro/Rooney
Mirallas in the team purely because I don't think Lookman's quite ready yet, and we desperately need some pace, any pace in this side.
I think that playing in a front two would get the best out of Sandro, but if you wanted to crowbar Rooney in to play behind you could do that instead. That can also easily be tweaked into the 4-2-3-1 Koeman prefers by simply playing Mirallas, Rooney and Sig as the three.
Arguably I'd put Holgate in for Jagielka, as well.