The contested work, which was initially labeled in the Philips ‘New Now’ online catalog as a work by Mark Grotjahn.

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A few weeks ago the artist Mark Grotjahn posted to his Instagram account a screenshot of a work that was set to be sold at the forthcoming Phillips “New Now” sale on September 19. It was designated as lot 168 and labeled as an untitled work by Mark Grotjahn, a painting in his style on 8 1/2 x 11-inch photo paper that had been inscribed “MG 10” on the lower right corner, indicating that it was made in 2010. It was estimated to sell for somewhere between $20,000 and $30,000.

But Mark Grotjahn said he didn’t think this is a work by Mark Grotjahn.

The Instagram post.

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“Yo Phillips. (. Dm. Me. ),” reads the caption of the Instagram post from September 2. “I’m not sure I made this. Either way it sucks.”

The post remains on Grotjahn’s account two weeks later.

It was unclear whether this was a formal complaint or perhaps a conceptual joke on the part of the artist, but it garnered hundreds of comments from those expressing shock or outrage over the idea of an auction house selling a knockoff. And now there have been concrete results of the Instagram post: Phillips has pulled the work from the sale.

“We are working with the artist’s studio to verify the work’s authenticity,” Michael Sherman, the auction house’s chief communications officer, told ARTnews. “In the meantime, we decided to remove the painting from next week’s sale until we arrive at a definitive conclusion.”

The online catalog for the “New Now” sale no longer lists an entry for lot 168, and in its place is a note that says “This lot is no longer available.” The information can be viewed still at the site Mutual Art.

Though the work pulled from the Phillips sale was of smaller size, Grotjahn’s large paintings sell at prices that make him one of the more expensive living artists in the world. This past May, at Christie’s Post-War and Contemporary Evening sale in New York, Untitled (S III Released to France Face 43.14), a work from 2011, sold for $16.8 million, establishing a new record for the artist.

Grotjahn.

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Grotjahn works exchanged privately can go for even higher prices. The collector David Geffen told the New York Times this summer that he lost out on one of the artist’s works that eventually sold for $22 million, and noted that he already has six.

“He’s the most important artist of his generation,” Geffen told the Times.

A representative for Anton Kern, one of the galleries that represents Grotjahn, declined to comment on the work pulled from Phillips. The artist is also represented by Blum & Poe, whose owners are in New York for an Alexander Tovberg opening tonight. They were in a meeting when a reporter called and have not responded yet to an email requesting comment.

When reached at Grotjahn’s studio in the Echo Park neighborhood of Los Angeles, a studio representative said during a phone call they would not be discussing the matter.