Now, don't go getting nervous. They asked you to help because they thought you could do a great job.   

Of course there are lots of new songs on a new album. But I'll bet their performance repertoire has lots of more familiar stuff. Hang in there with a positive attitude.

Hey hey hey Jerry, it's not too scary for you
Hey hey hey Jer, they want to doo-wop with you

well, you get the idea...