Frank Hoensch/Redferns via Getty Images | Kevin Mazur/Getty Images

By now the world knows about the blossoming friendship between Katy Perry and Stevie Nicks.

Last week, during a Fleetwood Mac concert, the lead singer dedicated the band's classic song "Landslide" to Perry and her boyfriend John Mayer, who were in the audience.

Recently Nicks opened up to ABC News Radio about first meeting the younger singer and the advice she gave her about navigating pop stardom in this day and age.

The connection between Nicks and Perry goes back to 2011, when the rock legend provided the narration for Perry's video "The One that Got Away." But the two only actually met for the first time this past fall, when they were both in London for performances.

Katy Perry Says Stevie Nicks Sees 'Straight Through My Soul'

"I met her after her rehearsal at 11:30 [at the hotel]," Nicks told ABC News Radio. "I thought it was going to be a 20 minute, 'Hey, how are you doing?' thing - and we sat for three hours until, like, three in the morning. And we pretty much talked about everything."

What Nicks found most interesting, though, was when Perry asked her about her solo career, which started in 1981 with the release of the album Bella Donna.

"She said to me, 'So when you did Bella Dona who were your rivals?'" Nicks told ABC News Radio. "And I was, like, speechless. I was, like, 'I didn't have any rivals.' And she said, 'Really? None?' I said, 'No…the girls in Heart [were] friends. Pat Benatar [was a] friend."

Stevie Nicks Returns with Secret Love and New Album

When Nicks asked Perry if she had rivals, the pop star replied, "Well, it's not us. It's the Internet."

She then told Nicks about the way that fans of various female pop stars will sometimes pit one against the other in ways the singers themselves don't condone.

"I said to her, 'Katy, let me tell you something. You don't have any rivals. So forget that. Never say that word again,'" Nicks told ABC News Radio. "'You don't have rivals. All of those girls? Friends. You'll probably work with all of them at some point. Friends.'"