Petrucci hit a screamer for victory over Leicester City.
He told the Peterborough Telegraph: "I knew when I hit it that it was going into the back of the net. I was so happy at that moment and even happier when we scored a winning goal as well.
"I was confident when the ball dropped to me that I could score as a few minutes before I had hit a good shot with my left foot that was going in until it hit (Wes) Morgan.
"It's a great result for us. We showed the quality and the character needed to get out of the bottom three.
"I am confident we will escape. I'm not saying it is going to be easy, but if we can play like this we will win many more games."