Andy Awford is adamant Paul Robinson is not a ‘panic’ recruit.
Pompey’s defence has attracted concerns during the final three pre-season fixtures having leaked eight goals.
Now Awford has moved to bolster his squad with the signing of Robinson on an initial one-month loan deal.
The Millwall central defender comes straight into the reckoning for Saturday’s trip to Exeter, providing further competition to Jack Whatmough, Ben Chorley and Joe Devera.
But Pompey’s boss has denied the switch was prompted by worries over his back four.
He said: ‘I have always said I am happy with what I have, but if the right player came along to strengthen then I would be interested.
‘When Paul became available it was somebody I felt could improve us as a squad so we got it done.
‘There was never a special need to go out and get another defender.
‘If a midfielder became available to make us better I would do that as well, as long as we didn’t break the budget.
‘In fact, I heard about his availability before the Charlton game so the wheels were in motion before then.
‘It is not a panic job, this is just a player I feel can improve us.
‘I don’t want it to be seen any other way.
‘Paul will bring experience, has played at a higher level and is good around the dressing room. As usual, I have done my homework.
‘I saw him play last season and I think he will be a good signing.
‘He played 27 games in the Championship last season. This is not a 19 or 20-year-old coming in from a development group, he is a seasoned pro.’
The centre-half positions in particular have come under scrutiny from supporters, with Whatmough and skipper Chorley starting against Charlton last weekend.
Devera and Alex Wynter have also featured in the role during the past three friendlies.
In Robinson, the Blues possess a firm favourite at Millwall who has amassed 362 appearances.
Formerly also captain of the Lions’ side, he is regarded as a tough-tackling old fashioned centre-half.
Now Awford has competition ahead of a busy schedule.
He added: ‘I had three recognised central defenders before Paul came in and a few others who can fill in there.
‘We now have another recognised centre half.
‘There are lots of games coming up and he improves that squad, definitely.
‘We have eight games in four weeks and if we go through to the next round of the cups you carry on with those midweek games in your schedule.
‘It was agreed between all parties we would see it for a month and assess it as we go.
‘If all three parties are happy for it to continue then Paul could stay on loan longer.’