“Dance Moms” alum Maddie Ziegler recently made her friend and former co-star, Kendall Vertes, cry.

On her Instagram account, Vertes shared a photo of herself with her best friend after the latter’s performance at Sia’s “Nostalgic For the Present” tour. Vertes was very proud of Ziegler’s performance, and this was why she ended up crying.

“Congrats to this cutie. Thank you for making me cry tonight and giving an unbelievable performance,” Vertes captioned the photo that showed Ziegler wearing the famous black and white Sia wig.

Meanwhile, Sia’s “Nostalgic For the Present” tour kicked off in Seattle on Sept. 29. Tickets for the upcoming shows are still available, except for Saturday, Oct. 8, and Sunday, Oct. 23.

The “Cheap Thrills” singer herself announced Ziegler’s involvement in her tour back in July via her Twitter account. The announcement didn’t come as a surprise to Sia's and Ziegler’s fans because the two have collaborated on several music videos. Ziegler was first featured in Sia’s music video for “Chandelier.” She went on to star in the music videos for “Elastic Heart,” “Big Girls Cry,” “Cheap Thrills” and “The Greatest.”

Aside from their professional relationship, Sia and Ziegler have also maintained a close friendship with each other. While speaking with Entertainment Tonight, Ziegler dubbed Sia as the “sweetest person” she’s ever met. “I feel like I’m just so comfortable with her every time I’m with her. I never feel like, ‘Oh my God, I’m hanging out with a celebrity.’ You would never guess she’s a celebrity if you didn’t actually know. She’s the most humble person and so caring, and she like, cooks for me! She’s such an amazing person,” she said.

Sia and Ziegler will also be working together in the movie, “Sister,” which was written by the singer a few years ago.