The cut-off point for clubs to complete their business is on Friday, October 16.
So far Pompey have made four signings. Sean Raggett was the first through the door, completing a permanent switch from Norwich after spending last season on loan at Fratton Park.
Cameron Pring following on a season-long loan from Bristol City, before Callum Johnson was recruited for around £200,000 from Accrington.
Then, last week, the Blues snapped up Michael Jacobs on a free transfer after he departed from Wigan.
While there won't be any wholesale changes at PO4 between now and the window shutting, we could still see couple of new faces arrive.
Pompey still want another centre-back, while a striker and central midfielder are other areas that could be bolstered.
The free-agent market could again be dipped into by Kenny Jackett and there are still plenty of unattached players available – although they can still be signed after the window closes.
We’ve taken a look at some of the unattached players who could fit the bill for Pompey…
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1. Richard Nartey
The centre-back had an impressive loan spell at Burton last season, making 29 appearances. He's still without a club since being released by Chelsea and Pompey are in the market for a central defender. Photo: Alex Davidson
2. Kenny Dougall
The midfielder helped Barnsley to League One promotion in 2019, having previously played for Sparta Rotterdam. Photo: Lewis Storey
3. Dominic Samuel
Another striker who remains a free agent. The former England youth international scored eight goals in 41 games when Blackburn were promoted from League One in 2018. Photo: Justin Setterfield
4. Ben Heneghan
Another central defender still without a club after his Sheffield United release. Heneghan spent the past two seasons at Blackpool and clearly makes the grade in League One. Photo: Jack Thomas