Anyone familiar with Sia's M.O. wouldn't have been puzzled by her hour-long main stage set at Coachella on Sunday (April 17) night. But judging by the crowd's response to her impressive but unusual performance, a majority of the weekend 1 Coachella fest-goers weren't quite ready for what a live Sia concert entails.

Like her music videos and live TV performances, Sia opted to remain in the background -- her face obscured by a half-white, half-black wig -- while belting out her inspirational, anthemic pop hits, leaving the task of visual entertainment to a rotating cast of dancers and celebrities.

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Kristen Wiig, Paul Dano, Tig Notaro and Dance Moms star Maddie Ziegler (who serves as Sia's stand-in for her emotional extremes) appeared either onstage or onscreen during the powerhouse vocalist's performance, miming out obtuse yet highly personal vignettes. While Wiig and Dano graced the big screen behind Sia, it was difficult to tell if the actors -- or simply professional dancers doing similar moves -- were onstage with her during her set. Regardless, the oddity of seeing something closer to performance art than pop music onstage during Coachella was captivating for thousands, but seemingly confounding for just as many.

As on any night at Coachella, the crowd gathered for the pre-headlining act (Sia in this case) consisted of countless fans waiting for the proper headliner (Calvin Harris). So this meant that many fest-goers -- already weary after a weekend in the desert heat -- waiting for a show filled with EDM staples and radio hits were subjected to some more challenging fare.

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While Sia certainly has dance/electronic crossover appeal thanks to her work with David Guetta, her extensive reliance on modern dance visuals meant that many waiting for Harris were somewhat confused by what was going on when Sia hit the stage.

Her introverted stage presence was certainly no surprise to fans, but the uninitiated at Coachella seemed mildly bewildered. While no one fled her set, many took the opportunity to reposition themselves in the crowd, chat with friends or get a drink. No one seemed outright irked by her quirkiness, but many remained disinterested, although polite. While Sia is gospel to many pop fans, she remains too idiosyncratic for others (some could be overheard wondering why she couldn't just show her face onstage like everyone else).

Regardless, her closing song, "Chandelier," pleased both sets of the crowd equally. One of her biggest hits and best vocal performances, "Chandelier" gave both devoted fans and casual listeners a reason to hold their arms in the air and sway to the music.