De Rossi said: "It's not easy to play Real, as they move the ball around like no-one else. They took the lead with a fortunate early goal, but Roma put in a great performance worthy of this crowd.
"We have learned something from our past errors. After going 1-0 down in Manchester we poured forward trying to turn it around and you saw what happened," he said of their historic 7-1 loss at Old Trafford.
"That thrashing matured us and we now have the patience to keep calm and reason our way back into the game."
The second leg is in Madrid on March 5 and Roma have the advantage thanks to this 2-1 victory.
"We have the quality and an organised midfield, so there's no reason we can't do well at the Bernabeu too."