Kristin Chenoweth Duets With Audience Member and a Star Is Born (Video)

Plucked from the audience to join the performer on "For Good" from "Wicked," singing teacher Sarah Horn stunned the crowd with a pitch-perfect rendition.

1.5 million and counting. 

That's how many people have now watched Sarah Horn, a Southern California-based singing teacher, duet with Kristin Chenoweth at the Broadway star's Hollywood Bowl engagement Friday night.

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That performance -- a rendition of Wicked's "For Good," in which the two witches of Oz bid each other farewell -- has deservedly gone viral. It was a risky moment of spontaneous dream-making that could easily have tanked, but instead provided the crowd with four minutes of sublime musicality.

"The 10,000-plus people of the Bowl faded away," Horn, a vocal teacher at California Baptist University in Riverside, writes of the experience on "There was no one else there. No noise. No people. I could hear the beautiful music of the orchestra but there was no one onstage, just Kristin and I."

Horn, who sang Elphaba's part to Chenoweth's Glinda, says she has been inundated with praise from well-wishers and work inquiries since the moment she stepped off the stage.

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Paul Geller, production director of Hollywood Bowl and Walt Disney Concert Hall, pulled Horn aside to tell her the song was "better than anything they could have planned." And Darren Criss, Chenoweth's co-star on Glee, chanted Horn's name backstage before posing for a photo with her.

Horn swears the moment was completely unplanned, despite several queries, including one from the Los Angeles Times, asking if she was in fact a plant.

"It was unlike anything I have ever experienced," Horn says.

Another angle:

Correction: A previous version of this story called the two witches sisters. They in fact meet in school.