Brilliant rook sacrifice!

In this bullet 2+1 game I found in less than 1 second a tactic you should know and which is hard to spot in time scrambles (I had 7.4 seconds and my opponent 8.1 seconds left on the clock). 

The tactic is at move 67. I sacrificed my rook to eliminate his passed pawn and deflect his rook which would permit me to promote my own passed pawn. He chose to eliminate my passed pawn but this way he gave me an easy endgame. If my opponent had played the best move he would have a kind of fortress (but not really a fortress) which would take me time to win and he would definately have the chance to flag me... However, he completely blundered and gave me an easy win...

Enjoy: