There seems to be bad blood between pop stars Taylor Swift and Katy Perry.

In a recent cover profile with Rolling Stone magazine, Swift revealed that the angriest song on her new album "1989" entitled "Bad Blood" is about another female singer she used to be friends with. She did not name who the artist is.

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She shared that they've known each other for years, but she was never really sure they were friends. ''She would come up to me at awards shows and say something and walk away, and I would think, 'Are we friends, or did she just give me the harshest insult of my life?'," she explained.

But then, Swift narrates, the unnamed star did a horrible thing to her last year, after which, the singer concluded that they were enemies. 

Swift clarifies that it wasn't over a guy, but rather it was because of business. "She basically tried to sabotage an entire arena tour. She tried to hire a bunch of people out from under me," she shared.

Swift, who has never been one to hide her feelings from the public, stated that she is actually non-confrontational and hates conflict. She says she is just trying to avoid the artist, but it has become very awkward because they run in the same circles.

Of course, the interview prompted netizens to do some sleuthing on who the singer could have been referring to - and it seems that Perry is the more likely subject of Swift's wrath.

Perry, who had split from singer-songwriter John Mayer this year, was supposedly the subject of Swift's song "Dear John". Swift had dated Mayer before Perry did.

Perry also hired three of Swift's backup dancers to work on her Prism tour while the "Red" singer was still in the middle of her own tour.

Lockhart Brownlie, one of the dancers, stated that Perry personally recruited them and that although they had fun dancing for Swift, "Katy contacted us. Obviously we were with Katy for 2 1/2 years, she's like family to us, so we were, like, 'absolutely'''.

Brownlie also shared that Taylor is "very protected", while Perry likes interacting with the crew.

Perry seems to have confirmed the feud with Swift as she took to Twitter to post, "Watch out for the Regina George in sheep's clothing". Regina George was the queen of mean in the movie, "Mean Girls".