We've been waiting for this moment. I know you have been too. "Dancing with the stars" is changing it up this season adding a fourth judge to the table. It is finally time to find out who it is. So... See More
We've been waiting for this moment. I know you have been too. "Dancing with the stars" is changing it up this season adding a fourth judge to the table. It is finally time to find out who it is. So come on out. ? Tonight's going to be a good, good night ? Yes. Yay! Hey. How are you guys? Look at you. How is it going. Good to see. You good to see you. Two-time champion. You know what it takes to win this thing, the mirrorball. It's been a few years since I've been back but obviously the guest judging for the last couple of seasons but, yeah, it's been a while since I've been back. I'm excited. Why did you want to do this. Oh, my gosh, well, "Dancing with the stars" is always been a part of my family. That's where it all began for me so it just kind of made sense and, you know, when I think about what Derek and I just did this summer on tour with move live on tour reconnecting with the fans and just the people that have supported me from day one from "Dancing with the stars," it just felt like the right time and the right kind of opportunity -- What are you most excited about. Oh, my goodness. I think just joining Len and Carrie Ann and Bruno, you know, robin, how fun it is on that panel and sometimes it's a little nerve-racking but it's fun too so I think the camaraderie between the judges and, of course, being a part of the show again. Having been on that dance floor, now that you're judging do you ever want to hop over the table and show them how to get it done? Oh, maybe not show them how to get it done but definitely the urge of dancing again, definitely comes back. I mean, that's, again, partly why I wanted to be a part of the show again was just being back on the road and everything just gave me that extra bit of oomph to start the whole dancing thing again. I have to ask what you are anticipating when it cops to judging your very own brother, Derek, who is now -- do you think you'll be tougher on him because you won't want to show bias. You know, I think that's a very valid question. I think that it's going to be how it was when I guest judged. It's not necessarily about Derek and the pro dancer. It's about a collaboration, the team effort. What they're doing as a partnership and really the celebrity and what they can do to improve each week. Yes, I am known to be a little honest and a little direct but I think that that's kind of my role as a judge in this because, you know, I want to see people improve. It's never with malicious intent but it's because I've been on the other side and I do want to be able to give criticism that they can take and learn and grow from. It's fun to see the celebrities get better and better each week and they take that advice and they're looking for constructive criticism. Absolutely and like I said I've been there but also, you know, back in -- when I was 10 years old I was competing and living in London and going to bla blackpool and world champions so I hope that whatever knowledge that I do have, it comes with grace and heart so -- Welcome back. Thank you.
This transcript has been automatically generated and may not be 100% accurate.