Julia Roberts tells Extra she was "so nervous" joining Taylor Swift onstage in August

By Michael Miller
Updated September 14, 2015 06:30 PM
Credit: Michael Loccisano/Getty

Julia Roberts is finally opening up about the night she officially joined Taylor Swift‘s posse, dancing onstage with the singer at one of her sold-out shows.

Roberts’ initiation into Club Swifty came on Aug. 15 at Levi’s Stadium in Santa Clara, California, where the actress joined Swift and legendary folk artist Joan Baez onstage to dance to “Style.”

“It was one of those crazy out-of-body moments – I can’t tell you anything that happened from the moment I came on stage,” Roberts told Extra’s Adam Glassman backstage at the Givenchy Fashion Week show. “I was so nervous!”

Confirming that the cameo was totally spontaneous, Roberts joked, “I would have washed my hair. I was, like, wearing a ponytail and leggings, tennis shoes … No, she was sweet enough to ask me before the show.”

The Pretty Woman star also revealed that her kids, Phinnaeus, 10, Hazel, 10, and Henry, 8, were the ones who convinced her to take the stage.

“She was very sweet with my children,” Roberts said of Swift, “and they had never been to a concert before and they were big fans.”

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“[Swift] said, ‘Would you mind coming onstage during the song and dancing?’ And I said to my children, ‘What do you think?’ ”

” ‘Oh Mom, you have to do it!’ ” she says they told her.

“And my youngest son said, ‘Only do it if you want to, Mommy.’ It was so sweet!”