The Australian midfielder managed to head home Stephen Dobbie’s cross in the 89th minute to beat the Posh 3-2 on the final day of the 2012/13 Championship regular season.
The win saw the Eagles to finish fifth on the tier two table allowing them to take on Brighton & Hove Albion in a two-legged playoff semi-final beginning on Friday night at Selhurst Park. Both sides have scored a 3-0 over the other at home this season.
On the flipside, Peterborough were relegated to League One but it could have been a completely different story if it wasn’t for Jedinak’s goal as a draw would have seen them finish 21st, above Barnsley on goal difference.
Lee Tomlin opened the scoring just prior to the half-hour mark for the Posh before Palace’s leading scorer Glenn Murray levelled with a penalty in stoppage time of the first half.
Nathaniel Mendez-Laing edged Peterborough ahead in the 63rd minute but Palace broke their hearts with Kevin Phillips making it 2-2 in the 83rd before Jedinak struck.