Jonson Clarke-Harris struck his 31st goal of the season early in the game before Josef Bursik saved a penalty just after the half hour mark.
Posh defended superbly as Charlton failed to create any clearcut opportunities in the second half..
RATINGS KEY: 10-Brilliant, 9-Outstanding, 8-Very Good, 7-Good, 6-Okay, 5-Poor, 4-Dreadful.
13.
HARRISON BURROWS (for Dembele, 87 mins): Excellent composure to help see the game out 7.
15.
DARREN FERGUSON: Clearly had his side fired up from the first whistle and defensively they were superbly organised. His starting selection was good and his use of substitutes was pretty perfect 8.
4 / 4