Lucian Freud's Pregnant Girl will highlight a sale of contemporary art at Sotheby's London on February 10.
The intimate work was executed in the early 1960s and depicts Freud's lover Bernadine Coverley, the mother of his daughter Bella.
Freud and Coverley met in a bar in Soho when she was just 17. They ended up having two children before splitting.
Bella told the Sunday Telegraph: "I like that my mother was so clearly in my father's thoughts and gaze, that at this time she was really important to him.
"She didn't talk about the painting but she was proud of it - I could tell by the tone of her voice when she first told me that it was of her pregnant with me in that picture."
The work is expected to sell for £7m-10m ($10m-14.2m).
Oliver Barker, Sotheby's senior international specialist in contemporary art, comments: "This astonishingly beautiful painting embodies the profound bond between Lucian and the mother of his two daughters.
"There is arguably no other portrait by Freud that is more gripping, more tender, and more laden with such emotional depth."
Freud's record at auction stands at £35.6m ($56.2m), set for his iconic Benefits Supervisor Resting at Christie's last year.
Other lots in the sale include an Abstrakte Bilder painting by Gerhard Richter that carries an estimate of $21m-30m.
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