Steve Cotterill has admitted it is unlikely there will be any more Pompey free transfer arrivals this summer.
David Norris and Stephen Henderson have so far been the only two catches from dipping into the out-of-contract player pool.
The Blues yesterday unveiled keeper Henderson on a three-year deal after agreeing an undisclosed compensation fee with the Irishman’s former club Bristol City.
And Cotterill believes the 23-year-old could be his final free transfer this summer.
The majority of quality freebies have already been long snapped up by rival clubs.
Others do not fit Pompey’s wage structure.
That scenario has left Cotterill struggling to identify many more targets in his push to strengthen his squad.
And he will now look to splash the cash to bring in more faces, before looking at the loan market.
Cotterill said: ‘It’s unlikely I’ll get any other frees.
‘They have gone, they were always going to go – I said this last season.
‘I’ll tell you when you have to do your free transfers – at the end of the previous campaign.
‘You need to get them all worked out, work on them before the end of the season and try to tie them up at the end of the season.
‘That is what you have got to do. Otherwise, forget it.
‘I have had players in mind but until the new owners came in there wasn’t too much I could do.
‘Other clubs have got there ahead of us and had things sorted for a while now. We’ve just had to watch.
‘We’ve missed out on some targets and I can’t see us getting any more in unfortunately.’
For Cotterill, a squad of 20 remains the target.
Despite the need to keep on strengthening, though, Cotterill has no intention of panic recruiting.
He added: ‘I have carefully picked who I want to get because I know they will fit into playing good football.
‘I don’t do scatter gun. I wouldn’t say I am a player collector.
‘I try to have a player who I know can do what I need him to do in my team framework.
‘The big obstacle you have to overcome is trying to integrate another half of a team with the team that are already here.’
Pompey – whose interest in Henderson was first revealed in The News last week – finally confirmed the keeper’s signing yesterday.
And after training with the club since Monday, the former Aston Villa trainee has vowed to push Jamie Ashdown for a starting spot.
Henderson said: ‘I’ve not come here just to make up the numbers and I’ll be doing everything I can to claim the jersey and keep it for as long as possible.
‘All I can do is continue to work hard and strive to improve so that the manager has a tough decision to make each week about who starts in goal.’