Coleman, who applauded the 3,126 City supporters on the final whistle, told the media after the game: "Jon showed great determination to get in there and then displayed great calmness to take the chance.
"There was no chance of us taking Peterborough lightly because they are bottom of the league. They have a new manager in who players are keen to impress and we were never going to get it easy.
"We got the battle we expected but, that said, I can't remember us being under too much pressure or our keeper having to make too many saves.
"We have been making a habit of keeping clean sheets lately and a lot of praise for that must go to the defence."