After practicing her dance moves, McPhee's character Karen and her fellow "Marilyn" actors take the stage to rock out to Adele's "Rumor Has It."
"I was super excited about that," McPhee told HuffPost TV when asked about the Adele cover. "I was a little bit like, 'Oh god, this whole record of hers is so epic and everybody is obsessed with it and everybody knows it. Everybody knows every little inflection she does and riff she does. I don't want to sound like I'm just imitating her.'"
However, it's not just a straight cover because "Smash" often puts its own spin on the material.
"You're always afraid if you can make it our own, but I think I did," she said on the "Smash" set in late January. "Everyone says it's an amazing moment in the show."
Check out Ryan Seacrest's exclusive sneak peek of McPhee's "Rumor Has It" performance below.