These things don't usually end so well!

On Friday, Kristin Chenoweth brought one lucky fan onstage at the Hollywood Bowl to sing the duet "For Good" from the musical "Wicked" -- and they sounded amazing!

Kristin called audience member Sarah Horn to come up for the rendition, and once Horn was onstage she shared with Chenoweth that she's actually a voice coach.

Check out the video above to see their lovely rendition of the popular ballad!

When Chenoweth realized Sarah's vocal ability she shouted, "Oh sing it, sing it!"," adding "Holy crap, harmony!"

You'd think this was planned -- but according to Sarah it wasn't. "I thought there'd be a plant [SIC] too!" Horn posted. "Apparently, Kristin gets a rush out of taking a musical gamble every once in a while. haha!," Sarah wrote on the YouTube page.

What do you think of their performance? Tell toofab in the comment section below!