Ferguson accepted that his team did not play particularly well in winning 2-1 but he was delighted with the way they defended, which gives the Posh boss hope heading into two tough away games at West Ham and Portsmouth in the next eight days.
"We have played better than that this season and lost, but we showed a different side to our character and proved that we are not just about attacking and scoring goals," said Ferguson.
"That's what made it the best result of the season for me. We will have to dig in and battle at times this season and we have now shown that we are capable of doing it.
"You can't have must-win games at this stage of the season, but that was as close as you are going to get purely because we have two tough away games coming up.
"Don't get me wrong, we are not going to West Ham on Saturday just to make up the numbers. We will try and win that game, and the way our back four and goalkeeper played (against Burnley) gives me confidence that we can."