Former American Idol contestant Justin Guarini will be a guest judge and performer on American Juniors.

In an interview with NBC's Access Hollywood, Guarini said: "I'm actually going to be a guest judge the first night, which is kind of weird, you know, who am I to judge people? But it’s kids and I have to give them mad props for even getting up there on stage and doing that. Having been in their position, I understand what they are doing."

Guarini was a runner-up in the first series of the highly successful American Idol, and has just released a self-titled album.