Dolly Parton joined Brandi Carlile on stage at the Newport Folk Festival in Rhode Island on Saturday night in a surprise co-headlining spot.

The performance was billed just as "The Collaboration" with two female symbols, Variety reports, leading the crowd to be extra shocked and delighted at the country icon's appearance.

Carlile introduced Parton as "the incomparable unicorn legend that is Dolly Parton." The duo performed a number of songs together, including a duet of Parton's classic "I Will Always Love You."

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Enlisting Parton was a labor of love, Carlile says.

“It was touch and go for a long time. It was like, ‘I sure would like to do that, and if I can, I will. I’ll let you know closer to Christmas,’" Carlile recalled. "Then Christmas came and went. ‘You know, I started my film schedule, and I won’t know until just before, so make sure you don’t announce me.’ So it was like that for a year of just digesting my stomach lining."

Then Parton gave her the most pleasant surprise ever.

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"I was in the studio with the Highwomen and I got an email and it said: ‘Just Because I’m a Woman,’ ‘9 to 5’ and ‘Eagle When She Flies,’" Carlile said. "And I was like, 'She’s gonna do it – oh my God!' And then like day before yesterday, she added ‘Jolene’ and ‘I Will Always Love You,’ and I was like, ‘F—k!'"

Carlile was on hand with her fellow members of the Highwomen, including Maren Morris, who Parton singled out for her success with "Girl."

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“Me and Rhode Island have a lot in common. We’re little but we’re loud," Parton said early in the set. "I know you’re in love with all these wonderful gals up here, and the men as well. Brandi, I’ve been a fan of hers for several years. My niece introduced me to Brandi several years ago and … when she asked me if I would come and do the festival I said I will do it if I possible can. And here I am.”

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After congratulating Morris on her No. 1, Parton gushed, “This is kind of all about the girls, and I looove being one of the girls. Of course I love my men too. Don’t get me wrong I’ve always had one of my own. I’ve had the same one for 53 years, as a matter of fact. But I love to be up here with all this girl power. I love to see us do good.”