It's apparently on between Justin Bieber and Patrick Carney.
On Sunday evening, the Black Keys drummer sort of mocked Bieber's Grammy snub, telling TMZ:
"He's rich, right? Grammys are for music, not for money... and he's making a lot of money."
The implication, of course? Bieber does not make solid music. He just brings home the bucks because young women buy his albums.
In response to the slight, Justin took to Twitter this week and wrote: "the black keys drummer should be slapped around haha"
Hmmm... he may have added the online-friendly haha - but why do we doubt Bieber is joking?
Those are fighting words, people. Literally! Who do you think would win a throwdown between Bieber and Carney?