NEW YORK (REUTERS).- The spotlight at this week's post-war and contemporary art auctions at Christie's and Sotheby's is trained on star offerings such as Jasper Johns' "Flag" and Andy Warhol's "Self Portrait."

But the most unusual work could be Yves Klein's monumental "ANT 93, Le Buffle (The Buffalo)," which is hitting the block for the first in its 50-year life on Tuesday.
The rare work from the French artist's signature "Anthropometrie" series is big, bright blue, and highly conceptual.

Long before Jeff Koons floated basketballs in distilled water and Damien Hirst sliced up a cow and suspended it in formaldehyde, Klein donned a tuxedo and presided over a scene featuring an orchestra's one-chord musical performance as a bevy of naked beauties strode before a Parisian gathering, smeared blue paint on themselves and proceeded to writhe on a large canvas.

The resulting "living brushes" work, a precursor to performance art that took hold in the 1980s, is now estimated to sell for $10 million at Christie's.

But it could well achieve more given the kind of free spending that marked New York's Impressionist and modern sales last week and the London auctions in February, when jewelry magnate Laurence Graff bought another Klein from the same series for $6.4 million, or more than twice the pre-sale estimate.

More than 9 feet wide, "Ant 93" is rendered in Klein's patented International Klein Blue, with which he became most associated. It was completed in 1961, shortly before his death at 34 from a heart attack.

An upcoming Klein retrospective at Washington's Hirshhorn Museum and Sculpture Garden, the first in the U.S. in 30 years, should stoke interest.

"Over the last three years his work has become increasingly popular with international collectors," who have helped drive the market's recovery, said Brett Gorvy, deputy chairman at Christie's Americas.

The owner, whom Christie's has not identified, decided to sell the work in view of strong prices in recent years for European conceptual art from the 1950s and 1960s, officials said.

Reports citing art experts have said the owner is C. Richard Kramlich, a San Francisco collector and co-founder of the venture capital firm New Enterprise Associates.

The auction record for a Klein is $23.6 million, set two years ago at Sotheby's at the height of the boom.