In-demand Louis Dennis will not be allowed to leave Fratton Park unless a replacement is identified.
The attacker is ready to quit Pompey in search of first-team football following a frustrating maiden campaign on the south coast.
In turn, the Blues would consider cashing in on a player they recruited on a free from Bromley 12 months ago.
Kenny Jackett has revealed enquiries over the availability of Dennis have been made during the summer.
But the 26-year-old’s proposed departure hinges on Pompey recruiting a number 10 alternative.
Jackett said: ‘There has been some interest in Louis, just enquiries, but if we were going to let anybody go now we would need a replacement.
‘Louis is here, he is competing for a first-team place and training well, but we must feel confident we can fill that spot.
‘In an ideal world that is what you have to do, you’ve got to protect the club.
‘It's just over a month before the Premier and Championship transfer window closes and then we have the rest of that month.
‘It’s increasingly frantic and difficult, but still possible to sign good players as well.
‘I wouldn’t want a big hole to appear in our group and then not be confident of filling it.
‘Louis has been okay, he is training hard and, like a lot of the players, will be waiting to see where he figures.
‘He is going to Ireland, he has come back fit and, like others, needs games to get sharpness.
‘We would need a replacement, though, before letting him leave.’