Torres played an hour for Atletico as they claimed a 2-0 win over city rivals Real Madrid in their Copa del Rey round of 16 first leg on Wednesday.
The 30-year-old, who was greeted by over 40,000 fans at his presentation, said he had a similar feeling in his first game back for his boyhood club.
"You always get butterflies in your stomach at times like these," Torres said.
"I got them the other day in the presentation and I got had them today."
Goals from Raul Garcia – a penalty – and Jose Gimenez put Atletico in control of the tie ahead of the return leg.
But Torres warned his side the tie was far from over as they prepare to travel to The Santiago Bernabeu on January 15.
"It was a great job. The second leg has to be outlined in a very similar way," he said.
"The clean sheet gives us many options, but a 2-0 in the Bernabeu is far from a definite result."
Torres added: "We are happy for many things: for the work of the team, for the atmosphere that we have lived and are still living at the Calderon."
