Nastasic admits that he has never played against a team like Stoke before but stresses the importance of not focusing too much on their strengths ahead of today's fourth-round tie.
He told the club's official website: "Of course, we know how difficult it is to play at the Britannia Stadium. Stoke are a well-organised team but we are prepared for a physical battle.
"In Serbia and Italy, there are no teams like Stoke, they are a product of English football and that is their identity, I guess. But I am confident that we are good enough to go there and win.
"I am looking forward to the game. The FA Cup is a competition that everybody always looks forward to at the club so for us it is very important."
The 19-year-old has featured heavily in his debut season at the Etihad Stadium, making 21 appearances in all competitions since signing from Fiorentina in late August.