Katy Perry's claws are out!

The singer spoke to Billboard mag about her much-reported fight with America's sweetheart Taylor Swift, saying, "If somebody is trying to defame my character, you're going to hear about it."

Last year, TayTay Tweeted about a fellow female musician as her "straight-up enemy," which everyone took to be a reference to pop rival Katy Perry. The next day, Perry responded with: "Watch out for the Regina George in sheep's clothing" -- a reference to Mean Girls, which clearing seemed to be a rebuttal to Swift.

So what brought on the vicious hatred? Katy reportedly "stole" three of Swift's backup dancers for her Roar tour last year. Swift responded the way she usually responds when someone does her wrong ... by writing a song about the "Fireworks" singer -- "Bad Blood."

Adding fuel to the flames, both singers dated bad boy John Mayer. And speaking of boyfriends, Katy's lover Diplo has even jumped into the fray, posting some Mean Girl Tweets of his own, directed at Taylor. Of course Taylor bestie Lorde came to her pal's defense and shot back at the DJ on social media, sending entertainment media into overdrive with their public display of nastiness.

Katy'll have to put this all aside this weekend, however, when she takes center stage at halftime for the Super Bowl XLIX on Sunday in Arizona. When asked about the once-in-a-lifetime gig, Katy said, "Everyone has been asking me if I'm going to be nervous before the halftime show," she told Billboard. "I'm like, I'm...human. This is the biggest event of my career."