"Your brain naturally turns to what lies ahead of you and dreaming is free," he said.
"Having already made history, it's on all our minds that this is not enough and we want to grasp the silverware, but to do that we first have to beat Russia again."
Spain beat world champions Italy 4-2 in penalty shootout to book a rematch with Russia, whom they trounced 4-1 in the first round of group stage.
"It's a bit of a trap to be playing Guus Hiddink's side again because I'd hate it if people thought this is an easy match simply because we won 4-1.
"We've seen all of their games since then and Russia have impressed, especially against Holland." said Casillas.
Casillas said he is looking forward to the rematch on Tursday in Vienna, "It's going to be a beautiful match because these two sides are both committed to attack, they share a football philosophy. Russia have impressed me."
"The key for us is to manage the ball and control the first half.This is a unique opportunity for Spain and we must seize our destiny." the Spanish goalie said.