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(Yahoo!) - Maroon 5 singer Adam Levine may be best known to some for judging aspiring singers on NBC's "The Voice." Now, however, he's taking those opinions to Twitter by judging Lady Gaga, but apparently she's not interested in any of his coaching.

It started on Friday with Levine calling out Gaga with the tweet suggesting she's not much of an artist:

He then upped the ante a bit:

Gaga, however, didn't take the criticism lying down, and mocked Levine right back:

However, the Levine-Gaga twitter "art" feud only went one round, with both soon moving on to other subjects.

On Sunday, Levine was impressed with a living legend, tweeting, "Paul McCartney. F*** YES!" However, we're not sure if Levine was catching up with Sir Paul's Saturday performance at the iHeart Radio Music Festival, or if he got hooked up with passes to see him play "Jimmy Kimmel Live" tonight. Today, Levine was busy plotting with his fellow judges on "The Voice," which returns to TV tonight, writing, "Seriously @xtina @CeeLoGreen it's time to take @blakeshelton down. He's due for a loss. It's getting old."

[PHOTOS: Maroon 5 Live at the iHeartRadio Music Festival]

Meanwhile, Gaga was on Twitter trying to ratchet up excitement for ARTPOP, her forthcoming album by quoting the lyrics of a new song called "Do What You Want (With My Body)."

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