But their awe was soon justified when the diminutive blond star belted out an operatic warm-up with composer and longtime Oscar telecast conductor Bill Conti.
The timpani player, for one, stood agog.
Today's recording session marked one of the key rehearsals for Conti, his 60-piece orchestra and the star performers headlining the Oscar telecast.
The mood was bubbly. The composer handed out pizzelles, a beloved Italian confection. Producer Gil Cates gushed over Chenoweth's performance of "That's How You Know." The musicians cheered when Oscar telecast director Louis Horvitz walked in, chanting "Lou! Lou!"
Still, there was a good bit of nervous energy hovering.
There's a greater sense of urgency coloring everything this year, though Cates and his team are making the best of it.
With just five days before the big show, there's still a tremendous amount of work to be done. The stage has been assembled and Jon Stewart has settled in with his team of scribes. At the Kodak Theatre today, lighting was fine-tuned and some of the more involved stage maneuvers were tested. Camera rehearsals start tomorrow.
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Though Chenoweth had been approached about doing the show, she wasn't officially booked to perform until last week. She had to change her shooting schedule on the Reese Witherspoon movie "Four Christmases" to be available.
In the hallway, after her recording session, Chenoweth was getting briefed on the elaborate stage set up for her production. But for the Broadway pro, this sort of deadline is manageable.
"This is just one song," she said, smiling. "It's a quick learn for me. It's what I do."
Besides, she added, there's only one Academy Awards.
"I've been on stages like Carnegie Hall, the Met, London -- everywhere," she said. "But this is a whole different ball of wax."