Christina Aguilera and Demi Lovato’s friendship is one for the books. A few days after the opening of her new Planet Hollywood residency on Friday, Aguilera revealed in an interview how important Lovato’s support is to her as a singer.

At the opening of Aguilera’s “The Xperience” in Las Vegas, Lovato was there to cheer her on. The 26-year-old singer fangirled throughout the entire event and even shared on her Instagram snaps and videos from the show.

“The queen herself,” Lovato wrote. “A perfect, perfect show. Couldn’t believe it was opening night because it was so smooth, flawless and sounded incredible. I was entertained the entire time and was so bummed when it was over until I was reunited with this beauty,” she added.

The young singer also revealed in another post that she was only 14 when she last saw Aguilera in a concert. “…I can’t believe how much life has changed since then,” she wrote. “Honored to call you a friend. Keep it up, queen.” At one point during the show, Lovato captured herself crying as her idol was singing her version of “Reflection.”

Christina Aguilera Christina Aguilera killed at the AMAs in her homage to Whitney Houston. ABC

In an interview following her Las Vegas show, Aguilera talked about Lovato and how the singer’s support has helped her get by on her worst days. “It’s incredible knowing that she grew up on my music and was a big fan,” she said.

Aguilera went on to share a story where Lovato attended one of her concerts and turned around in the audience to pretend that it was her concert. “It’s an amazing story, and I love hearing things like that,” Aguilera said.

Demi Lovato Demi Lovato attends WE Day Toronto at the Air Canada Centre on October 1, 2015, in Toronto, Canada. Isaiah Trickey/FilmMagic

“It was the ‘Back to Basics’ tour, and I was pregnant with my now 11-year-old son. Having those moments, sharing stories like that and hearing them is truly what just keeps me going on my worst days. It’s knowing that we are touching people here. We’re moving music along and helping inspire other people,” she added.

Aguilera and Lovato’s friendship started last year, after they worked together on “Fall In Line.” They performed the song together at the 2018 Billboard Awards and earned praises for their performance. Since then, the two have openly shown their support for each other’s projects.