If he's training well enough, Barkley should get the
for this one. Arsenal tend to struggle with his physicality when we're able get him on the ball in good areas.
If Koeman does decide to keep Ross on the bench again, I'd prefer to see Valencia, Davies, Dowell, or even Kone (if he's fit) play behind/alongside Lukaku. McCarthy/Cleverley were invisible there in our past two matches and I don't see either of them growing into that role (McCarthy looked pretty good alongside Barry, though).
Really, we just need someone who can help make the ball stick higher up the pitch or at least win a few fouls (we also need appropriate support for the more advanced players; you can't ask one or two players to hold the ball against four or five men consistently). I don't think it's a coincidence that our defensive record has gone to shit since we've been unable to keep the ball out of our defensive third.
Edit: So there's no way to use the word "n o d" anymore? Interesting. Enjoy the emoji, folks!