Mary Kate Olsen and Kirsten Dunst: Art Show Catfight!

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Miami's Art Basel convention, a cultural and social event held annually each December, drew celebs such as Paris and Nicky Hilton, Brittany Flickinger and David Katzenberg this year.

Also in attendance were Kirsten Dunst, 26, and Mary-Kate Olsen, 22, though they weren't exactly discussing art together, says Page Six.

An eyewitness tells the site that the pair got into a spat while sitting together at Audi's party at the Delano hotel in South Beach.

"They just kind of stared at each other for a long time and then started exchanging nasty words," says the source. "Then Olsen just got up and left. She's been going really late every night."

Oh, to be a fly on the wall for that argument. What could it have been about?

Another partygoer tells Page Six, "[Mary-Kate] looked like she had not brushed her hair in a week and she was chain-smoking the entire time and sitting like a sourpuss with her boyfriend. She was acting very oddly."

Dunst has had to endure several awkward situations recently. Last week reports surfaced that she was dating her collaborator on a political documentary, Jacob Soboroff.

Her rep swiftly insisted there is "no romantic involvement at all" between the two.

Dunst was also rewarded a temporary restraining order against Los Angeles native Christopher Smith, who has been allegedly stalking the actress.

A hearing is scheduled on December 22 to determine if Kirsten will receive a permanent restraining order against Smith.

Hopefully she will not need a secondary order against Mary-Kate Olsen.