Pompey are through to the second round of the League Cup for the first time in four seasons thanks to Miles Storey's goal in the first half of the tie.
Andy Awford made six changes from the Exeter match and deployed a wing-back formation to accomodate Alex Wynter and Dan Butler on the flanks with Paul Robinson making his debut alongside Joe Devera and Ben Chorley.
The decision to play Storey up front worked a treat as the Peterborough defence struggled to deal with the loan striker's pace whilst Craig Westcarr alongside him linked up well with the midfield and giving the visiting defenders a hard time.
It was Westcarr who combined with Butler to provide an excellent pass to Storey on the wing who took the ball into the box before slamming the ball into the bottom far corner of the net to give Pompey a deserved lead.
The full backs worked well in Awford's experimental system and Nigel Atangana pulled the strings in the centre of the park to highlight just how much of an assured performance this was against a team in the league above. Peterborough's only attempt on target in the whole half was ruled out for offside.
Darren Ferguson's men did come out stronger after the break and put the Pompey defence under pressure with Paul Jones having to make a save before a goal was ruled out for offside.
Storey was taken off midway through the second half due to a migraine but he's certain to start against Cambridge on Saturday after such an excellent performance.
It seemed like Pompey had killed the game when Westcarr stole the ball from a Peterborough defender and raced through on goal before striking the ball past Ben Alnwick but the referee cut the celebrations short by declaring that Westcarr had used his hands despite the assistant keeping his flag down.
Thankfully it didn't matter as Pompey were able to see out the rest of the game and the six minutes of "Fergie time" fairly comfortably and will now be in the draw for the next round of the cup which takes place tomorrow night.
It's safe to say that Awford's experiment worked and he now has a dilemma whether to stick with it or change the formation again. Certain players such as Butler, Wynter, Robinson and Devera made good cases for staying in the team after their performances tonight too. Westcarr also showed what he was capable of when played in the correct position so the manager has plenty of food for thought heading into Saturday's match.
Ben Chorley also deserves plenty of praise as he has come in for some stick in recent times but didn't put a foot wrong and timed every challenge perfectly.
But the whole team can be proud of themselves after an excellent performance. Let's hope for a good draw tomorrow but please, not Southampton!
Pompey Player Ratings
Paul Jones: 6 - Little to do in truth.
Alex Wynter: 7 - Slotted in well.
Paul Robinson: 7 - Worked well alongside Chorley.
Ben Chorley: 8 - Didn't put a foot wrong.
Joe Devera: 7 - Solid showing.
Dan Butler: 7 - Didn't look out of place on return to the side.
James Dunne: 7 - Battled hard.
Danny Hollands: 7 - Some clever passing.
Nigel Atangana: 8 - Seems like an absolute bargain.
Miles Storey: 8 - Gave the Posh defence nightmares.
Craig Westcarr: 8 - Excellent link-up play and physical presence was something Peterborough struggled to cope with.
Substitutes
Alex Bass
Adam Webster (Wynter 60): 6 - Didn't weaken the defence apart from one lapse of concentration.
Johnny Ertl
Nick Awford
Jack Maloney
Jed Wallace (Westcarr 75): N/A - Kept things ticking.
Ryan Bird (Storey 58): 5 - Didn't do much and still looks the weak link in the squad.