Steve Claridge believes Southampton will head into the south coast derby as favourites.
The long-time Championship frontrunners have hit a rocky patch in recent weeks.
Nigel Adkins’ side have taken just one point from a possible nine – in stark contrast to improving Pompey.
The Blues have suddenly discovered a bit of form, with a draw and two wins from their last three matches.
That has ensured they head into Sunday’s Fratton Park clash with their neighbours in buoyant mood.
But promotion-chasing Southampton are still 17 points ahead. And it’s that scenario which has convinced Pompey hero Claridge, below, that Sunday’s visitors are the slight favourites.
He said: ‘Pompey have found a little bit of form.
‘They’ve won their last two and Southampton have just dropped off their high standards, shall we say.
‘I don’t know how much that will level the playing field.
‘But I don’t think there’s anybody who’s going to have an easy game in this division.
‘Southampton will probably go into it favourites because of the form they have been in all season.
‘But Portsmouth are at home and they’ve got players who can raise their game and be a match for anyone.
‘They’ve got lots of Premier League experience and I think they’ve underachieved, it’s as simple as that.
‘If you get it sorted out there’s no doubt you’ll have a decent club at that level.’
Claridge made a total of 122 appearances and scored 37 goals for his home-town club.
But he never featured in a south coast derby.
He has attended many as a fan, however. And he expects the latest encounter to be a feisty occasion.
He added: ‘Fratton Park can be a difficult place on a day like that, because the atmosphere will be fantastic.
‘They’re always great games and, if you’re from one city or the other, then there’s always a little bit of extra spice.
‘If you’re a Southampton boy it’s always going to be a little bit spicy if you go to Portsmouth and vice versa.’