
They need at least one key reinforcement as it stands, and head coach Tonda Eckert has suggested that there will be more movement in and out.
The German wants to reduce the size of his squad from 27 senior players, admitting it is "too much", but business has been hard to do this year.
As many as nine players now have uncertain futures, and some would require direct replacements either to improve the team or boost depth.
Here is our assessment of the squad ahead of Tuesday's 11pm deadline...
Technical director Johannes Spors among St Mary's bosses (Image: Richard Crease)
Which players could leave Saints ahead of the deadline?
Aaron Ramsdale (very likely)
Saints are keen to offload the goalkeeper for a healthy fee.
Gavin Bazunu (very likely)
Bazunu is not part of Eckert's plans and Saints want to sell him.
Mads Roerslev (possibly)
The Dane has not made a matchday squad for Eckert and could go.
Yuki Sugawara (very likely)
Sugawara is not part of the plans at Saints and will leave for a fee.
Taylor Harwood-Bellis (likely)
Saints are open to selling for the right price, but there is no active bid.
Josh Quarshie (very likely)
The young defender is set to be granted a loan move for minutes.
Sam Edozie (unlikely)
Edozie has featured regularly for Eckert so far this season.
Ben Brereton Diaz (very likely)
Eckert confirmed talks are taking place over his departure.
Cameron Archer (possibly)
The in-demand forward is usually an unused substitute here.
Damion Downs (very likely)
Downs looks set to depart Saints after a nightmare first season.
Aaron Ramsdale has not been selected this season (Image: Matt Watson / Southampton FC)
Will there be any other outgoing business this week?
Unlike Charles and Harwood-Bellis, who were deeper into their contracts at St Mary's, they will only be allowed to leave in the event of a huge overpay.
However, Saints are likely to sanction an exit, either on loan or permanently, for under-21s defender Juan Larios, who is not part of the senior picture.
Romeo Akachukwu could go out on loan towards the end of the window, but Saints are waiting to see what happens with their squad before he goes.
Joachim Kayi Sanda and Princewill Ehibhatiomhan could also depart on loan for more senior experience, after their first men's loans last campaign.
Saints have rejected bids for Taylor Harwood-Bellis (Image: Stuart Martin)
What signings could Saints make ahead of the deadline?
Back-up goalkeeper (likely)
Saints will need another shot-stopper if Ramsdale and Bazunu leave.
Back-up right-back (possibly)
If Roerslev departs, Saints will likely have to replace him for depth.
Starting centre-back (likely)
Another one that hinges on an exit; a Harwood-Bellis replacement.
Depth centre-back (very likely)
Saints are set to sign Keven Schlotterback to replace Quarshie.
Competitive centre-midfielder (very likely)
Rotational attacker or striker (possibly)
Saints are unlikely to spend big but could use loan market to add more.
A Shea Charles replacement is the transfer priority (Image: Stuart Martin)
What incoming business should we actually expect?
Saints owner Dragan Solak was very clear about what his recruitment team would be allowed to do this summer, and so far it has been the truth.
He said they would sign a back-up number 10, which turned out to be Lewis Dobbin, and then there would only be replacements for key outgoings.
If Harwood-Bellis leaves the club, although there is currently no offer on the table to do so, then at least one centre-back will become a must-buy.
Solak said his "goal" was to build a squad just as good as last season, but he is not exactly going to say the scout's goal is to make the team worse, is he?
Saints may pull the trigger on a market opportunity, or a value loan player to bolster the squad, but we should not expect too much extra business.
Ultimately, it is up to Solak, so if Saints start slinging around big fees late in the window, it means the chairman is concerned by the start to the term.
Dragan Solak was pictured at St Mary's last weekend (Image: Stuart Martin)