After 12 years, Blake Shelton's final season on "The Voice" is here. And in somewhat of a full-circle moment, country star Reba McEntire is serving as a mentor during the show's upcoming Knockout round, which begins April 17.

Reba McEntire's history with 'Voice' coach Kelly Clarkson

McEntire also has a long history with "Voice" coach Kelly Clarkson.

In the new "Voice" teaser, the pair reflects on their friendship that dates back to 2002. In 2007, Clarkson performed a duet of her hit song "Because of You" for McEntire's 2007 album "Duets. "

"I am so proud of Kelly. She has grown as an artist, as a teacher, from when we first met ... way back," McEntire said in the "Voice" teaser. "She was a baby! Now she's just matured into this wonderful woman that I am just so proud of, and I love with all my heart."

McEntire and Clarkson have performed a number of duets together over the years, per NBC.com, but their relationship goes beyond musical collaboration — the two were even briefly related, through marriage.

McEntire married her manager and former steel guitar player, Narvel Blackstock, in 1989. Narvel Blackstock was Clarkson's former manager, and Clarkson married his son, Brandon Blackstock, in 2013, the Deseret News reported. This means that McEntire was Clarkson's stepmother-in-law, although that family relation only lasted for two years, as McEntire and Narvel Blackstock divorced in 2015.

Clarkson and Brandon Blackstock, meanwhile, finalized their divorce last year. But it appears that Clarkson and McEntire still have a strong friendship.

In the new "Voice" teaser, McEntire talked about her return to the show.

"It's always a lot of fun to give advice because I study people when they perform, and I want to be touched when they're singing to me," she said.

"That's the biggest thing — to capture somebody in the audience to where they're sobbing or laughing," McEntire tells a "Voice" contestant in the clip. "Get some emotion out of them, and you did it for me."