Kenny Jackett insisted Pompey will replace Ben Thompson if he returns to Millwall in January.
The popular midfielder is on a season-long loan at Pompey from the Lions.
Thompson has been in superb form during the Blues’ push for the League One title, making 19 appearances and scoring once.
The 23-year-old’s deal has a recall clause in it, however, meaning his Fratton Park stay could be cut short next month.
And Milwall boss Neil Harris is currently weighing up that option, with injuries mounting up at the Championship outfit.
Jackett stressed he hasn’t discussed Thompson moving back to the Den with his Lions counterpart.
But the Pompey boss is adamant he’ll bring in a new player if that's the case.
When asked whether the Blues would bring in a replacement, Jackett said: ‘I would think so.
‘Ben’s on a season-long loan with a recall clause in January, which is standard.
‘We’re thankful to Millwall for loaning him to us and he has done well.
'They’ll make whatever decision they need to make in January and we will abide by it.
‘The ball is obviously in their court. But we’ve been very pleased with him and we have to make sure we have a contingency if he does go back.
‘But, similarly, we hope he stays because he’s not just been a good player but a good person around the squad.
'I’ve spoke to Neil Harris on a regular basis. We haven’t spoken specifically just about Ben, but he has kept in touch to follow his progress more than anything.
‘It’s not one where we have had discussions specifically about January, but obviously from their point of view they need to do right by their club, which we understand.
‘Ben has been very good as player and brought personality to the group.
‘He’s formed a good partnership with Tom Naylor and Gareth Evans in that triangle of the midfield three.’