The 26-year-old actress said as much in an interview Wednesday on The Late Late Show with James Corden. Olsen is a longtime fan of the 25-year-old singer, and recently had an awkward encounter with Swift at a mutual friend's birthday party.
"I really love her, and earlier in my ballet class, I was doing a dance sequence to her music," she recalled. "And I just talked at her for like a long time. I think I blew it because we didn't exchange phone numbers or anything."
"She was asking me which song [I was listening to in class], and I couldn't remember the song title, and I wasn't going to sing it for her!" she continued of the embarrassing exchange. "I'm still nervous thinking about it right now."
Swift is known for her friendships with such celebrities as model Karlie Kloss and actress Selena Gomez. The pop star gave fans a glimpse into her friendship with singer Ed Sheeran by sharing a screenshot of a goofy text message conversation with the star.
Olsen last appeared as Wanda Maximoff, aka Scarlet Witch, in new Marvel movie Avengers: Age of Ultron. The actress will reprise the role in Captain America: Civil War, and is also scheduled for Hank Williams biopic I Saw the Light with Tom Hiddleston.