Ariana Grande teased on her Twitter that something big was happening at her Atlanta Sweetener concert last night, and she wasn't overselling it. Grande brought up her Victorious co-stars Matt Bennett and Elizabeth Gillies to perform with her. "The most special show to me yet. Truly," Grande wrote on her Twitter after. "Love u. This was too much to process and don’t know what to say yet but so grateful and thrilled. Love u forever @LizGillies @MattBennett."

Grande and Gillies, who played Cat Valentine and Jade West on the 2010-2013 Nickelodeon kids' show respectively, sang "Give It Up" from the show on stage.

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VIDEO: Ariana and Liz Gillies performing ‘Give It Up’ tonight at #SWTAtlanta pic.twitter.com/oF5ucJZFdz — Grande Tour News (@GrandeTourNews) November 20, 2019

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I WITNESSED LIZ GILLIES AND ARIANA GRANDE SING GIVE IT UP LIVE

MY LIFE IS COMPLETE #SWTAtlanta pic.twitter.com/XtpdsQS73r — Lizeth (@_liz_eth) November 20, 2019

Here's them performing it on Victorious for a real throwback:

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Bennett, who played Robbie Shapiro on the show, sang "I Think You're Swell" on stage, and fans lost it.

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VIDEO: Matt Bennett performing ‘I Think You’re Swell’ with Ariana tonight at #SWTAtlanta pic.twitter.com/NLDl5KiVMl — Grande Tour News (@GrandeTourNews) November 20, 2019

Here's the original clip for reference:

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Gillies and Bennett joined Grande again during her finale performance of "Thank U, Next" and the three posed together backstage.

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VIDEO: Matt Bennett and Liz Gillies joined Ariana onstage for ‘Thank U, Next’ tonight at #SWTAtlanta pic.twitter.com/uN1P4Ish4Y — Grande Tour News (@GrandeTourNews) November 20, 2019

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Liam Hemsworth's new girlfriend Maddison Brown was in the crowd and shared her own photo from the night on her Instagram. Brown and Gillies are co-stars on The CW's Dynasty, which shoots in Atlanta.

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Grande's Atlanta concert comes after she canceled her Sunday show in Kentucky due to illness. Grande's fans applauded her will power to continue working through sickness but also implored her to take a break if she needs to for her health:

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deal. promise. thank u for caring. https://t.co/bXago1HkbI — Ariana Grande (@ArianaGrande) November 19, 2019

Grande wrote on her Instagram Story over the weekend that she was suffering from a weeks-long bug. “Hi my loves so I’m still very sick," she started, via People. "I’ve been sick since the last London show. I don’t know how it’s possible but my throat and head are still in so much pain. I sound okay I’m just in a lot of pain and it’s difficult to breathe during the show. I am seeing my doctor and trying my v best to get better for tomorrow’s show. The last thing I would ever want to do is cancel a show at this point with so few left. I’m truly cherishing every moment of this…I just really don’t know what’s happening with my body right now and need to figure it out. Please take this as a gentle heads up…I don’t want anyone to feel blindsided tomorrow if God forbid I can’t make the show happen."

"I’m on all the meds," she continued. "Getting IV drips, doing everything I possibly can to pull through. Mom and friends are taking good care of me. Just a scary feeling. Love you with all my heart and will keep you posted."

Alyssa Bailey News and Strategy Editor Alyssa Bailey is the news and strategy editor at ELLE.com, where she oversees coverage of celebrities and royals (particularly Meghan Markle and Kate Middleton).

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