NEW Single on iTunes Sia's new single features a mind-boggling performance from 11-year-old dancer Maddie Ziegler. The elaborate routine was choreographed by Ryan Heffington; Sia co-directed. Sia has steadily become pop music’s most in-demand songwriter. She’s penned tracks for everyone from Christina Aguilera (“You Lost Me”) to David Guetta (“Titanium”) to Ne-Yo (“Let Me Love You”) to Rihanna (“Diamonds”) to Britney (“Perfume”) Beyoncé (“Pretty Hurts”). Really, which major pop player hasn’t tapped her for a tune? Yet after all this time, apart from some high profile features and a one-off soundtrack single, she’s not yet released a solo single of her own since 2010.