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…
You can subscribe here to get the latest news and transfer updates from Fratton Park - and to support our local team of expert Pompey writers.
13. Devante Cole
A mercurial talent but the striker has never got back to top form since leaving Fleetwood for Wigan in 2018. Played nine times for Doncaster last season before his release. Photo: Martin Rickett
14. Andre Green
Someone who Kenny Jackett rated highly even if he didn't feature as much as he'd have liked during his loan spell in 2018-19. The winger was released by Villa this summer, although Pompey are well stocked in wide areas. Photo: Joe Pepler
15. Jack Hobbs
The centre-back was, in fact, born in Portsmouth and has an array of Championship experience. Photo: Harry Trump
16. Victor Anichebe
The ex-Everton and Sunderland man hasn't played a competitive game since 2017 but recently said he's in the best shape of his life Photo: LINDSEY PARNABY/AFP via Getty Images