Pompey have sought advice from a former England manager and a current Premier League boss during their managerial hunt.
Iain McInnes has revealed the duo had been consulted as the Blues attempt to identify the ideal candidate.
Pompey’s chairman would not reveal the identities of the pairing, who gave up their time to talk to football operations consultant Darren Simmons.
Simmons, who is not paid by Pompey, has been assisting chief executive Mark Catlin in drawing up a managerial blueprint to present to the club board.
McInnes believes it demonstrates the thoroughness of the process to select Guy Whittingham’s replacement by the Blues.
The interview stage today heads into day two prior to tonight’s visit of Wycombe in a rearranged game.
Among those invited for talks have been Richie Barker and Steve Coppell, Chris Wilder, Steve Claridge, and David James and Hermann Hreidarsson.
Others are also on the short list as Pompey seek to finalise a decision by Monday, having received 40 to 50 ‘serious’ applicants.
In the meantime, McInnes, who has sat in on the interviews conducted so far, is adamant the process has been conducted professionally.
He said: ‘I keep hearing we have either been cowards for sacking Guy or brave for sacking Guy.
‘I would love to know what we are, perhaps somebody can please tell us! As a board, we decided a change had to be made and now are conducting a thorough selection process to identify the best candidate for the job.
‘As part of that, Darren Simmons, through his contacts, has spoken to an ex-England manager and also a current Premier League manager.
‘It would be unfair for us to reveal who these people are – but they were only too willing to pass on some of their football experience.
‘Their views have been priceless in the process so far and we thank them for their time and assistance.
‘This was never going to be a quick decision, despite what I keep hearing from people, and it has always been our intention to conduct it thoroughly and professionally.
‘We have done our homework, we really have.
‘And we have taken some excellent advice from some very impressive people along the way.
‘Obviously, we are aware this is an extremely important appointment for the football club – and have treated it as such.’
In addition to the applicants, there is also the option for Pompey to consider David Connolly or Andy Awford for the manager role.
Tonight’s visit of Wycombe is set to be Awford’s last as caretaker boss before a permanent appointment is made.
Meanwhile, Connolly has made no secret of his desire to one day become a manager.