Ellen DeGeneres and Heidi Klum Perform as Sia and Maddie Ziegler for Halloween -- Watch!

This video is unavailable because we were unable to load a message from our sponsors.

If you are using ad-blocking software, please disable it and reload the page.

How did Heidi Klum do this dance?!

The America's Got Talent judge joined Ellen DeGeneres on the talk show host's Halloween episode on Monday, where the two dressed as Dance Moms' Maddie Ziegler and Sia, respectively.

WATCH: Kelly Clarkson Slays A Capella Cover of Sia's 'Chandelier,' Hilariously Wears Wig During Performance

Michael Rozman/Warner Bros

"Well, as you can tell, I'm Sia, and the problem is I can't really see ya," DeGeneres joked for the audience before bringing out Klum. And not only did they pretty much nail the outfits, they even prepared a routine!

"We've rehearsed for over seven minutes, so this should be good," DeGeneres said, before the two launched into an abridged recreation of Sia's "Chandelier" video.

Michael Rozman/Warner Bros
Michael Rozman/Warner Bros
Michael Rozman/Warner Bros

MORE: Heidi Klum Teases This Year's Halloween Costume -- 'It's Going to Be a German Theme'

Watch the whole performance below.

That's impressive, Heidi!

While the German model was noticeably winded after the dance, DeGeneres -- who did not have much to do, beyond lip sync -- commented, "She's in pain, and I can't see."

Meanwhile, Sia and Ziegler in their music video attire have been popular Halloween costume choices in 2016!

On Friday, Kelly Clarkson donned a Sia wig and launched into her own (fantastic) rendition of "Chandelier."

PHOTOS: Best Halloween Costumes of 2016

Sia, who has been retweeting fans who dress up as her for the holiday, has been overjoyed with the Halloween love.

On Sunday, Sia retweeted DeGeneres' costume photo, after praising Clarkson for her performance on Twitter, writing, "Oh yes @kellyclarkson you just made my day! I love you!"

PHOTOS: Spooky! Stars Get in the Halloween Spirit

Happy Sia-ween!

Watch the video below for Chrissy Teigen's daughter Luna's adorable costume.

Related Gallery