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.
"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."