The quarter-final could have been blown wide open if he had converted the penalty just 30 minutes in, but Carlos Tevez scored in the second half to secure a 3-0 aggregate victory for Manchester United.
"I was a little emotional at that moment, not so much for the incident, but because they were still chanting my name at the end of the match.
"That means so much to me, especially after such a nightmare of a game."
Reporters mentioned that even Roberto Baggio had missed important penalties in the past, but De Rossi replied: "That is scant consolation.
"I am so upset about this, it is one of the worst moments of my career.
"In any case, we played a great Champions League this season and now, just as the fans were singing to us, we will try to win the Scudetto."
