"Beyoncé is the most talented human being on the planet," Paltrow, 38, tells Harper's Bazaar U.K. in its March issue, on newsstands Thursday. "She has so much mastery over what she does. It's not even confidence – it's on a whole other level. It's mind-blowing."
Beyoncé, 29, was trying to be helpful, but Paltrow at times found her example intimidating. "I watched her [perform] a lot to see how she did it, and I was like 'S---! I can't do that!' " Paltrow says.
The actress ended up becoming a very believable country singer for the film role. But she was still terrified when called on to perform live at the CMA Awards in November.
"Two weeks before I did it, I was dying," she says. "I couldn't sleep. I couldn't eat. I was like, 'Why would I say yes to this? What is wrong with me? What kind of maniac would agree to do this?' "
Courtesy Harper's Bazaar