Midfielder Nick Carle turned from villain to hero, after he bought down Palaceâ€™s Tom Soares in the box, handing a penalty-kick to the home side.
Unfortunately for Palace supporters, Ben Watson, (who had scored earlier to edge in front in the 2nd leg and square the ledger on aggregate), missed the spot kick. This gave City a massive look in as they pounced on any mistake, and eventually took the overall lead (3-2 on aggregate) by tying the game in extra time.
The miraculous victory was rounded off when Carle set up and laid off the ball for Michael McIndoe to give City a two goal buffer (4-2 on aggregate) with just ten minutes remaining.
The win puts the Robins into the Championship play-off final on May 24, where they will meet either Hull or Watford.
It looks like it may be an all-Aussie final as Hull take a two goal advantage into their match at home tonight, and a win would see Tigers striker Richard Garcia up against Carle in the promotion decider.