Sirigu deputised in goal during Italy's 2-1 win over England in their FIFA World Cup opener on Saturday after captain Buffon was ruled out with an ankle injury.
Buffon is doubtful to return for Italy's second Group D clash against Costa Rica on Friday, but Sirigu said he would happily step aside should the country's most-capped player be deemed fit to play in Recife.
"As far as I am concerned, it's not a battle between me and him," Sirigu told reporters. "In the national team everyone has to give the good they have inside them.
"I think I have given my contribution to Italy and I am happy to have done it.
"Sometimes you have to be realistic and look at who is alongside you.
"I am relaxed and calm, I don't know whether I will play (against Costa Rica). We're all hoping Buffon will be back and that he will be on the pitch.
"We want him back not only in the dressing room, but also on the pitch for his quality and charisma."
Sirigu added: "In the national team you don't think about having a precise role, you are just happy to be there.
"For an Italian it's always something more because everyone feels Italian, it's good to be part of this group. I'm not thinking about replacing Buffon.
"I don't know whether it's a mistake, but it's not the reality. Buffon is first choice, he is not just a player but something more."
