ET is in the studio with actress KRISTIN CHENOWETH, who's rehearsing for her Oscar night performance, where she'll sing "That's How You'll Know," one of the three songs nominated from the hit movie 'Enchanted.'

"You can play Carnegie and the Met, and places all over the world, but this is the Oscars, and it's a totally different ball of wax," she tells ET. "So I'm just trying to keep myself from getting too nervous!"