A first half tap in from Bim Pepple secured all three points for Plymouth Argyle at the Weston Homes Stadium.
Sometimes games of football can be free-flowing and easy on the eye, but in truth, this Sky Bet League One encounter was more stop than start and ultimately it was the visitors who headed back to the South West with all three points.
Peter Kioso was shown a second yellow card deep into the second half on a day where Posh saw eight cautions and also lost the services of Tom O'Connor and Harry Leonard to injury.
Early diagnosis on O'Connor points to a potential hamstring issue while Leonard was stretchered off after landing horribly on his neck following an aerial challenge - assessments continue on him.
The game itself was devoid of any real clear-cut opportunities, Lorent Tolaj, who committed four fouls before finally being cautioned in the first half, guided a volley wide of the target early on while Sorinola was denied by a sprawling Alex Bass save.
At the other end, it was mainly long-range efforts from Posh with Archie Collins firing wide and Matt Garbett comfortably denied by Hazard in the Argyle goal.
Posh ended the first half strongly with plenty of sustained pressure, but it was wayward efforts at the end of it, Carl Johnston firing over from a well-worked corner and Kyrell Lisbie heading over.
The goal when it came was a soft one, O'Connor, who injured himself in the process, couldn't get the ball back to Bass, Tolaj intercepting and squaring for an unmarked PEPPLE to slot into an empty net.
The second half was more of the same, Bass did well to keep out Sorinola with his legs while Tolaj fired high and wide when well placed. Posh continued to push to try and force an equaliser, but again, there wasn't much in terms of chances.
Kioso was shown a second yellow card for an alleged late challenge and will miss the weekend trip to Wycombe Wanderers, while manager Luke Williams will be spending the early part of the week assessing those in the treatment room.
Posh: Bass, Johnston, Collins, Khela (sub O'Brien-Brady 76min), Lees, Lisbie (sub Hayes 76min), Morgan (sub Aderoju 59min), Leonard (sub Frith 76min), Garbett, O’Connor (sub Nevett 23min), Kioso. Unused subs: Smith, Dornelly,
Plymouth Argyle: Hazard, Ross, Edwards, Tolaj (sub Szucs 90min), Mitchell, Boateng, Galloway, Pepple (sub Watts 84min), Curtis, Sorinola (sub Wiredu 90min), Ralls. Unused subs: Ashby-Hammond, Paterson, Amoechi, Benarous.
Half-time: Peterborough United 0-1 Plymouth Argyle
Full-time: Peterborough United 0-1 Plymouth Argyle
Attendance: 8,684 (1,234 Plymouth fans)
Referee: Ben Atkinson