But it turns out that Gaga had actually called the screen legend ahead of time to touch base about the performance.
Andrews, who said she'd "been a fan for a long time" of Gaga, was knocked out by her performance of "The Sound of Music," "Edelweiss,” “My Favorite Things” and “Climb Every Mountain.
"The minute I got home from the Oscars I called her. ... I confirmed that I thought she was fantastic and had done a wonderful job, and I couldn't thank her enough," she said. "She really did a wonderful thing with the medley. She sang superbly and then so lovingly handed me the evening on a platter, if you know what I'm saying."
"As I say, I've been a fan for a long time but she's now a very new good friend," she added.
Andrews is also confident that Gaga could have a career in musicals if she wants it.
"I've been saying it ever since," she said. "I have, truthfully!"