Katy Perry asked Stevie Nicks a question about her career that left her speechless, according to ABC News Radio.

During an interview with the radio show, Nicks talked about connecting with Perry, but not actually meeting the "Roar" singer until fall of 2013. Nicks described a conversation they had while performing in London.

"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."

Perry went on to ask Nicks about the start of her solo career with the 1981 release of her album "Bella Dona". Nicks was originally a member of the band Fleetwood Mac.

"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."

Nicks then asked Perry who she believed to be her rivals, in which the pop singer responded that she didn't have any, but the Internet. Perry explained to Nicks that fans would compare two female artists and want to stir drama against them.

"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. "'You don't have rivals. All of those girls? Friends. You'll probably work with all of them at some point. Friends.'"

Nicks and Perry first collaborated in 2011, when the singer's camp approached her to narrate Perry's music video for "The One that Got Away."