Marchetti explained how he felt at making his World Cup debut when replacing the injured Buffon.
"I was on alert, as Gigi felt this problem in his back during the warm-up. I knew that I could come on at some stage," said the Cagliari shot-stopper earning his fifth cap.
He came off the bench at half-time and was rarely tested in a 1-1 draw with Paraguay.
"My thoughts travelled to many places, I was preparing myself mentally straight away and trying to be very concentrated.
"Gigi told me to relax, that I'd do well and he reassured me.
"It's only normal that playing at international level there is a different atmosphere but I tried to focus only on the pitch and the game at hand, so that helped me to stay concentrated."