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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9. Omar Bogle
Would you like to see him back? Bogle scored four goals in 14 games during his loan spell at Pompey in 2018-19. Still without a club after being released by Cardiff. Photo: Daniel Chesterton
10. Jordy Hiwula
The striker enjoys a goal at Fratton Park, scoring in his past two visits for Coventry. The 25-year-old bagged 17 goals in 61 games for the Sky Blues. He has plenty of pace, which would give Pompey something different up front. Photo: Morgan Harlow
11. Joel Lynch
The experienced centre-back left Sunderland in the summer, after making 21 appearances last season. He had been training with Charlton earlier this summer. Also left-footed, which is what Pompey are looking for. Photo: George Wood
12. Ruben Sammut
The midfielder had a period on trial at Pompey during Kenny Jackett's first season in 2017-18. However, he struggled to get a look in at Sunderland last season and would likely be a bit of a project Photo: John Walton