Two goals from Erik Husekepp either side of a Jason Pearce header saw Pompey record their second away win of the season in emphatic fashion at London Road.
The Norwegian, playing just behind Marko Futacs in a 4-4-1-1 formation as a replament for Dave Kitson, was part of a team that were set up to hit Peterborough on the break and that tactic worked perfectly.
The home side had the first chance when Grant McCann fired wide early on but that was as good as it got for them as it was one way traffic for the rest of the half.
Pompey were ahead just after five minutes after Kelvin Etuhu got the better of his full back for the first of many times and whipped a dangerous ball in the box which was me by the head of Futacs.
Goalkeeper Joe Lewis couldn't hold the ball and Erik Huseklepp forced it into the back of the net at the second attempt to send the support in the terraces behind the goal ballistic.
The siege continued as Pompey found it easy to break up Peterborough attacks and hit them on the break due to the amount of time and space the players had to pick their passes.
Had more players been in the box or gambled by making a run across the 'keeper, it would have been expected to score again given the amount of crosses being delivered into the box. As it was, a nervous Peterborough side managed some last-ditch clearances to deny Pompey a second goal.
Red & Black shirts continued to pour forward and Liam Lawrence forced a great save from Lewis with his drive from outside the box whilst Hayden Mullins and Etuhu also had a pop from distance.
It was all too easy for Michael Appleton's men as the hosts again left themselves wide open to a counter-attack which Pompey forced a corner from.
Lawrence whipped the ball in and Jason Pearce came from nowhere to head the ball into the corner of the net and give the visitors a well deserved two goal lead going into the break.
As the terraces filled up further with late arrivals due to problems with trains outside Peterborough, the game descended in a low-key affair as Darren Ferguson's men pushed for a goal, but rarely troubled Stephen Henderson.
The Pompey stopper had to push McCann's free kick around the post and gather another effort from Tommy Rowe but in truth it was comfortable for him and the rest of the Pompey players who continued to put Peterborough on the back foot.
Huseklepp then began the "fire drill" with his second goal of the game as he effortlessly turned Ryan Bennett and beautifully curled the ball past Lewis into the corner of the goal.
Futacs could have made matters worse for the fans leaving in their droves but could only shoot wide when he had time to pick his spot.
It didn't matter as the final whistle blew to end a fantastic performance from a Portsmouth side that worked hard and stuck to a game plan which worked perfectly.
It's safe to say that 'Appy got his tactics spot on yesterday and had his players been more clinical, we would have easily had five or six.
Not that any Pompey fan could have complained after that result yesterday. I personally haven't enjoyed an away day like that in a long time due to a superb atmosphere in the terraces (bring them back!) ignited by the best Portsmouth performance since hammering Leicester 6-1 last season.
Yes, Peterborough were verging on dreadful but some superb individual performances from Pearce, Etuhu, and Huseklepp combined with some exceptional work ethic meant that our players made theirs look terrible at times.
The result now means that Pompey have leapt Peterborough in the table into 16th place and more importantly sees a ten point gap open between us and Nottingham Forest in the relegation zone.
How important might this result be should the club be forced into administration? The next few days may also see a number of players sold to pay the bills so we can expect a tough couple of days.
But for today, we can just bask in the glory of a superb win that may well be decisive at the end of the season should the club survive the winding-up order.
Pompey Player Ratings
Stephen Henderson: 6 - Little to do.
Tal Ben-Haim: 8 - Gave 100% and carried a threat going forward.
Jason Pearce: 8 - Goal capped impressive performance, one which may see him sold by Tuesday.
Ricardo Rocha: 8 - Won almost everything.
Greg Halford: 7 - Did well in unfamiliar left back role.
Liam Lawrence: 7 - Continues to get better.
Hayden Mullins: 8 - Contribution to breaking up attacks cannot be understated.
Joel Ward: 6 - If he was sharper he might have had a goal or two.
Kelvin Etuhu: 8 - Caused Posh defence allsorts of problems.
Erik Huseklepp: 9 - Perhaps Appleton has found his best position, needs to show this sort of performance more often.
Marko Futacs: 7 - Held the ball up well and posed a threat.
Dave Kitson (Futacs 82): N/A - Late cameo but will struggle to get back into the side now.