Nyatanga played in the Rams' defeat by Portsmouth on Saturday and said: "I felt quite calm, to be honest.
"I've been in other pressure situations, obviously internationally, my debut for the club when I was younger and things like that. I was actually quite cool because you lose energy when you're nervous."
He added: "I worked hard while I was at Barnsley and thought my form was quite good.
"Then I got called back and have been working hard. So when the chance comes, you take it with both hands."