Her music video dancerMaddie Zieglerwas onstage to lend extra flair to the surprise concert.
Sia first performed The Greatest in her customary wig and an oversized fuchsia bow with multicolored ruffle dress.
Ziegler performed choreography almost identical to the music video that was displayed on a screen next to the stage.
Credit: Ollie Millington/Redferns
Ziegler danced with a troupe of four others.
Ziegler performed alone for this number as she bounced off of mattresses and table and chair set-up.
via GIPHY
Sia performs next in Cleveland, Ohio as she starts herNostalgic for the Presenttour September 10.
