It has taken a wicked deflection and a fortunate ricochet to break down Pompey in recent weeks.
The outcome has been successive defeats, leaving Paul Cook’s side nursing their lowest League Two position since August.
Regardless, the Blues possess the mantle of the joint-best defensive record in their league.
What’s more, nobody has this season claimed more League Two clean sheets than goalkeeper David Forde.
And from that solid foundation the Blues are seeking to force a way into the automatic promotion spots.
Certainly the defence has come under scrutiny from supporters on occasions, likewise the selection of Millwall loanee and ever-present Forde.
Yet even runaway leaders Doncaster Rovers cannot come anywhere near to matching Pompey’s against column so far.
Admittedly, Darren Ferguson’s side have scored 19 times more than the Blues, having played one game more.
It’s a prolific haul which ensures they top the table by five points, having also inflicted the double on Cook’s troops.
Nonetheless, Pompey’s return of 28 goals conceded can be equalled only by Luton and Blackpool.
In fact, only five clubs in the entire Football League can better such a defensive record.
In the Championship, leading pair Newcastle (23) and Brighton (24) are proving resolute, as are eighth-placed Derby (22).
Elsewhere, Bolton (22) and Bradford (26) possess an impressive League One record, although are presently in the play-offs.
Despite Pompey’s eye-catching defensive return, they have not registered a clean sheet in their last four matches.
Although, in mitigation, Wycombe’s Scott Kashket’s heavily-deflected shot was enough to wrong-foot Forde last weekend.
Against Exeter, Michael Doyle’s clearance clattered off the shin of Danny Rose to fall generously to David Wheeler for the winner.
Previous to that, Gavin Massey’s stunning first-time shot proved nothing more than a wonderful consolation to struggling Leyton Orient in their 2-1 defeat at Fratton Park.
Irrespective of the lack of recent shut-outs, Forde has now claimed 11 for the campaign.
No League Two keeper can better that, although Exeter’s Christy Pym does share the honours.
The duo have recorded two more than a chasing quartet which currently have nine league clean sheets to their name.
They include Jamal Blackman (Wycombe), Sam Slocombe (Blackpool), Luke McCormick (Plymouth) and Artur Krysiak (Yeovil).
Doncaster stopper Marko Marosi, currently out with ankle ligament damage he sustained against Pompey, has seven shut outs in 22 games.
However, in terms of clean sheets per match, Pym is far ahead of second-placed Forde.
The Grecians stopper averages 64.71 per cent, with his 11 coming in 17 outings, while Forde (39.29 per cent) is clear of Blackman in third.