I think it'd be a big mistake to sit back in this one and let Southampton dictate terms all day. TP probably won't do it but I'd start a 4-4-2.
GK
(Myhill/Palmer?)
Nyom/Dawson/Evans/Gibbs
Phillips/Krychowiak/Barry/Chadli
Rodriguez/Rondon
To be fair Soton play a lot like Leicester and us (to a lesser degree) by sitting back and trying to hit on the counter attack; they struggle when teams do the same so sitting back is arguably the best tactic in this case. To be fair it's a pretty moot point though as we will set up to play like that regardless.
We need Phillips back in and possibly McClean as we need pace in the side to be more effective on the counter, I'd play Chadli just behind the striker whether that's Rondon or Rodriguez.
I'd be tempted to go for 4:2:3:1 or 4-1-4-1
Myhill
Nyom Dawson Evans Gibbs
Barry Krychowiak
Phillips McClean
Chadli
Rondon
Subs: Palmer, McAuley, Hegazi, Yacob, Livermore, Brunt, Rodriguez.