Roma take a 2-1 lead to Madrid and Spalletti says: "We can't limit ourselves to defending and trying to stop them scoring.
"We have to score because we are expecting to have big problems if we try and hold the result at 2-1."
Francesco Totti's recent form has been inspirational and he will need to be at his best again in Spain.
"Totti is stupendous for us," Spalletti admitted. "He is the luxury player who picks the passes and is always ready to invent. He is our heart and soul."