Rochdale are nursing the worst defensive record in the top four divisions.
But Kenny Jackett has warned underestimating a Dale side rejuvenated since the departure of Keith Hill.
The League One strugglers have conceded 79 times so far this season, more than any Premier League and Football League club.
It's a defensive weakness which has underpinned a season of struggle, last month costing the long-serving Hill his job.
However, replacement Brian Barry-Murphy has rejuvenated the side to inject hope of avoiding relegation.
Rochdale have taken three wins and two draws from his six matches in charge, a sole defeat occurring at the hands of Sunderland in the last minute.
What’s more, their once-porous defence has conceded just five goals during that period.
Jackett said: ‘Don’t underestimate any opposition – and realise to get points you have to work very hard at your maximum.
‘Certainly looking at Rochdale since the new manager took over, there have been some good results, including three wins and two draws.
‘He’s had a very good run and any problems they’ve had, whether defensively or going forward, they have addressed in recent weeks.
‘Obviously it’s something which needed to be done because they have been in and around the relegation places during the course of the season.
‘We will fully respect Rochdale on Saturday, they had a great win at Accrington in the week and have been good performance-wise in recent games.
‘Maybe they might have had to put in a little bit more emphasis on defence because that’s where you're struggling, and similarly the other way.
‘In the end it’s a balance of the two which gets you the results and the confidence.’
Meanwhile, Jackett isn’t satisfied with his own defence at present.
For Pompey’s 43 goals conceded is the highest out of League One’s top five.
He added: ‘I try to work 50/50 in terms of defence and attack. It’s a very obvious thing to say, but I go for equal importance.
‘We are second-top scorers in the league next to Luton – but I do think our defensive record could be a little bit better.
‘We haven't necessarily had sloppy ones, but there have been two late goals against Walsall and two against Wycombe, those type.
‘We could have a better goals against column than we’ve got.’