As for me, I bet we see Naismith on one wing, particularly with our midfield injuries.
I could see us coming out with a 5-4-1 formation for this, with Heitinga sweeping. If Mirallas and Gibson both miss out:
Jagielka Heitinga Distin
Osman and Naismith, despite their limitations, will both track back into wide areas when needed. With Gibson out and Barry ineligible, we don't have many options in the centre. Pienaar and Mirallas both injured would force us to play a bit more narrow, as I doubt Deulofeu is ready for a full 90 with the defensive responsibilities he'd have to pull for Man City away.
I suspect Mirallas makes it, though, perhaps in place of Osman or Heitinga.