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LOS ANGELES (KTLA) — An audience member brought down the house Friday at the Hollywood Bowl after Broadway star Kristin Chenoweth invited her onstage to sing a duet.

Sarah Horn, accompanied by her family and a friend, said she was enjoying the show at the outdoor venue when Chenoweth began interacting with members of the audience.

Kristin Chenoweth and Sarah Horn performed a “Wicked” duet Friday at the Hollywood Bowl.

“Do you know the song ‘For Good’?” the singer asked Horn, referring to a song from the “Wizard of Oz”-inspired musical “Wicked.”

“Yes, it’s one of my favorites,” Horn replied, prompting Chenoweth to bring her onstage.

As they stood in front of the L.A. Philharmonic, facing the audience of thousands, Horn revealed that that she teaches voice lessons for a living. (She is an instructor at California Baptist University and the Riverside Youth Theatre.)

“Yay,” Chenoweth said, before embracing Horn in a hug.

The orchestra kicked off the song, with Chenoweth singing Glinda’s first two verses. Horn, who towers over the 4-feet-11-inch Chenoweth, affectionately rested her head on the head of her musical idol.

When Horn began singing Ephalba’s verse, Chenoweth “leaned back and dropped her jaw,” Horn said later. “She knew I was a voice teacher but didn’t know if I did well in the execution or not.”

The audience was just as surprised, and roared its approval.

“Oh, sing it. Sing it.” Chenoweth said at one point. And then: “Holy crap — harmony.”

The two singers went on to finish a thrilling duet that would not have been out of place on Broadway itself. As they took their bows, the crowd showered them with thunderous applause.

“That voice is teaching our young people,” Chenoweth said after Horn left the stage. More applause.

The performance was captured via iPhone by Horn’s friend Mike Kestler, who uploaded the video to YouTube. It has since gone viral after being heavily upvoted on the social news website Reddit.

Read Horn’s first-person account of her “surreal” experience here.