Less than half a minute remained when Paul Scholes rose to head the last-gasp only goal that left City’s players devastated and put a dent in the bid for a Champions League place.
City were pipped 4-3 at Old Trafford in the League to a goal in the seventh minute of time added on, then saw Wayne Rooney grab a late, late strike in the Carling Cup semi-final.
Mancini said: “Football is very cruel sometimes. Sometimes you win, sometimes you lose in the last minute. But we never win in the last minute!
“I hope next time it can happen for us, that we win the game like that when we don’t deserve to win the game.
We have improved a lot from the last derby but in the last two games against them we didn’t deserve to lose. They score a goal always in the last second
“Now we are disappointed and I am angry, because I know football very well and sometimes you don’t deserve to lose. Tomorrow I hope that will pass, and we will start over again.
“If you don’t play well and you lose the game, that’s one thing. But when you play as well as the other team and have chances, and lose in the last seconds, you are very, very unlucky.”
