Demi Lovato turns 27 years old today (August 20), and she celebrated the happy occasion by hitting up Ariana Grande's Sweetener concert at London's O2 Arena on Monday, August 19.

Lovato took to social media during the show to fangirl over Grande, posting several clips of the "Boyfriend" singer's performance to her Instagram Stories. "Yasssss Queen," she wrote alongside a brief video of Grande singing "God Is a Woman." "ARI YOU QUEEN," she wrote along with another short clip. At one point, Lovato even took off her shoes because she was dancing too hard!

But even though it was technically Grande's night to shine, the "7 Rings" songstress was happy to share the spotlight with the birthday girl. In a video Lovato shared on Instagram, Grande and the rest of the Sweetener crew dedicated their pre-show prayer to the "Sorry Not Sorry" singer. "This was too sweet not to post," Lovato captioned the clip. "... before show prayer they did this for my bday ... I'm so so proud of you @arianagrande. You fucking killed that!!! I love you tons."

Of course, Grande was thrilled that Lovato — who's also managed by Scooter Braun — made it out to the show. "love u so much," she commented in response to the video. "thank u for coming !!!!" But that's not all they had in store for Lovato's special day.

Backstage, Grande, Braun, and the rest of the crew celebrated the "Confident" singer with cake and a lot of singing. "Okay, last one before bed," she wrote. 'They literally filmed/sang happy birthday twice and @scooterbraunSTILL forgot to press record ... @arianagrande's face is everything and this video is a perfect glimpse of how fucking happy and rad my birthday is this year."

"So so happy," she continued. "And I love my new family. Thank you guys, love you." Happy birthday, Demi!