Before Lauren Alaina chased her own dreams to Hollywood on the 10th installment of "American Idol," she watched Carrie Underwood win the show's fourth season. While Carrie has known of Lauren for a considerably shorter time period, she still feels a connection to the 17-year-old.

"All of us 'Idol' people, we're all part of this club," Carrie says. "All the people that have come to Nashville since their days on Idol, everybody is genuinely talented and genuinely nice, and Lauren is no exception."

Having traveled this road, the elder 'Idol' is protective of her younger counterpart. "I hope in some ways I can maybe be like big sister," Carrie explains. "Whatever she's gonna do, I've already been there, I've done that. Maybe I can be like, 'Stay away from this, and do more of this, and take more pictures!' It's always fun to just be able to talk to her and see that bright-eyed ... just reminds me of myself when I was just coming off of 'American Idol'."

The Oklahoma native already has one sisterly duty under her belt: writing the Georgia native's next single. The tune, "18 Inches" -- which Carrie co-wrote with songwriters Kelley Lovelace and Ashley Gorley -- will be released to radio on July 16, and Lauren can't hide her excitement.

"It's amazing to have an artist like Carrie Underwood, whom I look up to so much write my single," beams Lauren. "Kelley, Ashley, and Carrie all did a wonderful job writing such an incredible song. I feel so honored to be able to bring to life the beautiful story within the song."

It's a special honor for the superstar as well. "I've had co-writes go on other people's albums before, but this will be my first single," she recognizes. "I've never had that before. It's always been really cool when someone else wanted to record one of my songs that I helped write, but to actually possibly hear it on the radio at some point, that's gonna be really cool, and Lauren is so amazing and does such a great job. It's so wonderful that that song found a home with her. Even she and her mom, they're like, 'This is our song. Like, this is all about us.' It just fits her really well."

Watch Lauren Perform '18 Inches' in Our Studio

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