Sia Scores Her First No. 1 Single at Age 40, Will Reunite With Maddie Ziegler on Tour

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The pop star is making history.

Sia is hitting the road with her music video muse.

The Australian pop star tweeted on Monday afternoon that Dance Moms star Maddie Ziegler will be joining the Nostalgic for the Present tour, which begins Aug. 4 in Moscow, Russia. The North American leg of Sia's tour begins in Las Vegas, Nevada, on Sept. 23.

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The 13-year-old performer will be dancing on the tour, Sia's first one in five years, just like she's done in three of the 40-year-old singer's music videos. "I’m SO excited and grateful to be joining @Sia for the #NostalgicForThePresentTour and perform across North America," she tweeted.

Ziegler performed alongside Sia on Saturday Night Live last year, and with Kristen Wiig at the 2015 GRAMMYs. She also starred in music videos for "Chandelier", "Elastic Heart" and the singer's first No. 1 single on the Billboard Hot 100, "Cheap Thrills," which also features 43-year-old musician, Sean Paul. According to research done by the Huffington Post, this is the first time in nearly 16 years that a woman over 40 has landed the top spot on the charts.

Mariah Carey came close at age 38 when her song, "Tough My Body," hit No. 1 in 2008.

While Sia's fan base is growing, Ziegler might still be her No. 1 supporter. According to ET's source, she left Dance Moms to continue working with Sia, and is set to star in a film project written and directed by the entertainer, titled Sisters.

"She's literally the sweetest person ever," Ziegler told ET. "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.'"

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