The shot-stopper was drafted into the starting lineup a matter of hours before kickoff after Gianluigi Buffon was ruled out through injury.
Despite playing only his ninth senior game for the Azzurri, Sirigu believes that he did a solid job against the English.
"I soon got over any anxiety I had," the 27-year-old told FIFA.com. "My teammates helped me a lot, which is one of the things that makes this side what it is. As soon as I went out on to the pitch for the warm-up I felt nice and relaxed."
Italy continue their campaign against Costa Rica on Friday.