A self-portrait painted by Lucian Freud when he was just 21 is expected to fetch up to £3m when it goes under the hammer at Sotheby's in London in June.
The painting shows "the beauty and innocence of youth", Sotheby's said
Man with a Feather "represents a defining moment of Freud's early artistic maturity", Sotheby's said.
The work, showing a distracted Freud holding a feather in front of a stark landscape and a yellow house, will go up for auction on 22 June.
The artist is now considered by many to be Britain's greatest living painter.
The auctioneers said the painting, created in 1943, was "one of the most important contemporary works to come up for auction in recent years".
"It has a candid and touching intimacy that anticipates the artist's lifelong obsession with uncovering the inner humanity of his subjects," according to Sotheby's Cheyenne Westphal.
"Man with a Feather shows the beauty and innocence of youth contrasted with the confusion and anxiety surrounding his first experience of love."
The artist sold the painting to art critic Robert Melville in the late 1940s and has never been offered for sale on the open market.
The contemporary art auction will also feature works by David Hockney, Leon Kosoff, Damien Hirst and Frank Auerbach.