Adam Lambert + Chris Daughtry return to American Idol this week

American Idol welcomes back two of its most popular alumni Tuesday night: Chris Daughtry and Adam Lambert. The two will advise the contestants in a "Boot Camp" segment led by judge-turned-mentor Randy Jackson. Randy says he wanted Chris and Adam to help the contestants this year because, unlike him, they've actually competed on the show.

"I've been doing this show since it started so I have a wealth of knowledge," Randy said in a conference call with reporters. "But they were actually in the trenches of people that we were actually judging, so they could tell it from a completely different side."

Of course, there are literally more than a hundred American Idol alumni who've made the top 10 over the years, but Randy said that Chris and Adam can offer a unique perspective, because neither of them took home the Idol crown, but went on to top the charts.

"They're each equally successful and they weren't the winners their seasons," Randy said. "So they've gone on to amass great careers that are still running strong, and they weren't even the winners. So I wanted the kids to see that -- see their knowledge, see their sense of self, where they are now, where they've grown, what they thought when they were on the show, auditioning. It's just such an insight that I think none of the contestants have ever really had."

Chris evidently enjoyed working with this year's crop of hopefuls: he tweeted a few days ago, "Gotta say I'm excited about this season of @AmericanIdol ...first time in a while. Gonna be a great one!" And Adam tweeted, "Had a Blast mentoring on @AmericanIdol can't wait for u all to see it this week!"

Randy says that during the "Boot Camp" segments of the show, he talked to the kids about trying to stay focused in the middle of all the distractions that come with the live shows. "You got cameras in your face, you got 500 people in the audience, you got all the chatter from social media," he said of the challenges the kids face. "You got your friends and family, you got millions of people watching on TV. We really broke it down and went through everything that we could...I think it really helped the kids a lot."

As for whether or not he misses being a judge, Randy says he was happy to step out from behind the table and leave things to Harry Connick Jr., Jennifer Lopez and Keith Urban. "When I walked away I was really done with it," he says. "I'd done everything I thought I could do. I couldn't even figure out another way to say stuff."

He added, "I was really happy, that I was on for 12 seasons as a judge and I'm happiest now about this new role as a mentor, 'cause that's kinda what I do anyway. As a record producer, as a manager of artists and a talent manager, it's what I do: nurture talent. So, this is the most natural fit for me."

On Tuesday night, the Top 15 girls will perform; on Wednesday, the Top 15 guys will do the same. On Thursday, we'll find out who the Top 10 finalists are, and the judge will announce their wild card picks to round it out to a Top 13.