Britney Spears and Demi Lovato ‘aren’t really singers’ says John Legend. Duets v X Factor USA feud alert

John Legend has some choice words for X Factor USA's new judges Britney Spears and Demi Lovato.

X Factor USAX Factor USA's new panel has already been criticised. Copyright [Wenn]

This week it was officially announced that Britney Spears and Demi Lovato will join Simon Cowell and L.A. Reid on the X Factor USA panel.

The Fox show isn't the only singing competition on TV in the US, with ABC launching a new reality singing competition called Duets, which pairs judges with contestants for duets on stage.

[Related article: Britney Spears finally confirms place on X Factor USA panel joining Demi Lovato, Simon Cowell and LA Reid]

John Legend is one of the judges and has already started a rivalry between the two shows.

Talking about X Factor USA's new judges, he told E!: " It's interesting when people, you know, are judging singing competitions when they aren't really singers."

Oooooh. Saucer of milk.

Duets panel, John Legend, Kelly Clarkson, Robin ThickeDuets panel John Legend, Kelly Clarkson and Robin Thicke. Copyright [Wenn]

John Legend will be joined by fellow judges Kelly Clarkson and Robin Thicke on the new show.

Robin Thicke was more friendly, saying: "Oh come on, everything Britney does, she excels at. Demi is a lovely young lady, and I'm sure they'll do nothing but make the show a lot more fun to watch."

Kelly Clarkson added: "I'm excited for both of them. I'm a big fan of both of them. Both of those girls are super sweet.

"I think it's fun for them too to just be more out in the public eye again. I think those two are two you really want to root for and you really want them to succeed, so I think that's exciting."

Now that The Voice UK and Britain's Got Talent battle is over, it looks like we've got X Factor USA and Duets feud to take up the mantle.