Kenny Jackett has conceded Pompey are set to lose Nathan Thompson.
The right-back is still to sign a new deal at Fratton Park, with his two-year contract expiring on June 30.
James Bolton became the Blues’ first arrival of the summer earlier this month on a free transfer after leaving League One rivals Shrewsbury.
That prompted the vast majority of supporters to come to the conclusion Thompson will be heading elsewhere, having shelved contract negotiations in February.
Although the tough-tackling defender is still to find a new club, Jackett admitted he doesn’t expect Thompson to be on the south coast next term.
Speaking to the Blues’ website, the boss said: ‘The addition of James Bolton does naturally cover Nathan Thompson.
‘I haven’t read that Nathan has signed anywhere. But, from our point of view, it looks like he is heading for pastures new.
‘James has been brought in with that in mind.
‘At 24, he has a good balance of experience in the division but has hunger to do well and step up to a big club, so I’m really looking forward to working with him.’
Thompson made 78 appearances and scored once for Pompey after arriving from Swindon in June 2017.