The Gunners have turned their form around in recent weeks under Mikel Arteta, with the younger players thriving to produce a team playing with freedom and energy.
While Ralph Hasenhuttl’s side bounced back from defeat to Leicester City last weekend with their mid-week victory over Shrewsbury in the third round, thanks to goals from Dan N’Lundulu and James Ward-Prowse.
Saints are two points ahead in the league and one place above the Gunners in ninth, though they have played a game more. And the sides could not be separated at the Emirates earlier this season with Pierre-Emerick Aubameyang cancelling out Theo Walcott’s opener.
Arteta admits the Gunners are looking at strengthening during the January transfer window: "We are in that process now. We have done the first part more or less and we are focusing now on the second phase. Obviously this market and the context makes it difficult, but we are looking at options and we will see what we can do.
"We are looking at various positions because the movement we have made in this window with some players leaving the club has left us a little bit short in certain areas. So if we can, we will do it and if we can't, we will keep going with what we have."
Here’s everything you need to know ahead of the match.
When is the game?
The match kicks off at 12:15pm GMT on Saturday, 23 January 2021.
Where can I watch it?
The game will be screened live on BT Sport 1 and BT Sport Ultimate. Subscribers can watch the fixture via the BT Sport app and desktop website. Coverage will begin at 11:45am.
Southampton XI: Forster, Walker-Peters, Bednarek, Stephens, Bertrand, Diallo, Ward-Prowse, Armstrong, Walcott, Ings, Adams
Arsenal XI: Leno, Bellerin, Holding, Gabriel, Cedric, Elneny, Xhaka, Pepe, Willian, Martinelli, Nketiah
Southampton - 21/10
Draw - 23/10
Arsenal - 13/10
Arsenal are rolling right now but Saints will be confident of advancing in this well-matched tie. We’ll lean towards the home side in a close one, which could go to extra-time, but Ings being available is the difference-maker, so we’ll go with the hosts to advance with a 2-1 victory.