You can't play Gomes and Lemina together IMO. They both want to do the same thing and wander forwards. Lemina needs to sit and be told not to go forward if it happens, but he's struggled with playing out from the back too and giving the ball away, so I'm not sure he can do it reliably and consistently enough compared to Andre. Who is much better receiving the ball in tight spaces than anyone else on the team and has a decent pass on him.
Got to be Gomes/Andre for me.
The two wide players you may as well just draw them out of a tombola for all the difference it'll make. Personally I'd like to see Forbs and R.Gomes given a decent go. But the jury is out on both of them and do you want to be gambling on them both in a must win game?
Can you play Cunha left and Doyle behind Larsen? Or do you push RAN further forward again and rotate the right hand wide player during the game? I think that's what I'd prefer, and start with R. Gomes and use Forbs off the bench with his pace.
Whoever plays they're going to need to be able to play a decently high press as Southampton like to piss about with it and keep possession in their own half. I think R.Gomes will suit that better than Forbs or Sarabia due to his defensive history at wing-back.
........................... Sa
Semedo - Bueno - Dawson - Toti
................ Andre - J.Gomes
.... R.Gomes - Cunha - Ait-Nouri
....................... Larsen