Posh were dealt a blow as they fell behind after just 13 seconds, Malik Mothersille responded before the break with his first league goal.
Archie Collins restored the lead with ten to play and an injury-time double from Jonson Clarke-Harris sealed the three points.
RATINGS KEY: 10-Out of this world, 9-Brilliant, 8-Excellent, 7-Very Good, 6-Okay, 5-Poor, 4-Stinker
1. JED STEER
Had a brilliant night which saw him save two penalties albeit both were taken poorly. He also set up the third for Jonson Clarke-Harris with a long ball upfield. 8 Photo: Joe Dent
2. HARRISON BURROWS
A very slow start to the game not at all befitting of League One's player of the season. Too many looses passes and did not find his usual quality of delivery. 5. Photo: Joe Dent/theposh.com
3. RONNIE EDWARDS
Not to his usual high standards, caused a lot of problems by the powerful Lawal. He was caught the wrong side of Lawal for the opening penalty and even though there was a bit of a battle between the two, the decision to award the spot-kick was a nonsense as the ref was fooled by a flop. 6. Photo: Joe Dent
4. JOSH KNIGHT
Also gave away a penalty but his looked to be a fairer decision for hauling down Promise Omochere. Stood up better to the powerful front line when they decided to come forward. 6. Photo: Joe Dent/theposh.com