The music world was abuzz with the release yesterday of Katy Perry's new single "Roar," but today the excitement is all about her duet with on-again, off-again boyfriend John Mayer, 35.  Their love duet is called "Who You Love."  Perry has thanked her fans on Twitter for her success.

"Who You love" is from Mayer's upcoming album, "Paradise Valley," and features a cute callback lyrics.  He sings:

"My girl, she ain't the one that I saw coming / Sometimes I don't know which way to go / And I tried to run before but I'm not running anymore," he sings.

Perry, 28 answers, "My boy he ain't the one that I saw coming / And some have said his heart's too hard to hold / And it takes a little time / But you should see him when he shines."

The couple have been dating since last summer.  Back in April, Mayer confirmed their breakup, but then in June's "Vogue," Katy Perry said she still had feelings for her ex.  Then in July, Mayer hinted to a reunion during a concert, according to MTV.  

Perry talked about her little "love giggle" at the end of the track.

"I think that's just a love giggle," Perry explained. "It's like the ones that Mariah Carey had in 1990 and stuff like that . . . Yeah I think I was going for that, I think I was just so happy, I love that song." 

Check out their sweet duet here:

 

Mayers "Paradise Valley" comes out next week on August 20, and Perry's long-awaited "Prism" comes out October 22.  Her single "Roar" released yesterday, and she took to Twitter to thank her fans for its success.