A rare Picasso masterpiece from his prized Blue Period - with a concealed image on the reverse- is set for auction.
The oil-on-canvas painting La Gommeuse will be sold at Southeby's New York next month with an estimate of $60 million (£30m).
Works from Picasso's 1901-1904 Blue Perion rarely come up for sale, Simon Shaw of Sotheby's said. The painting had been in the private collection of US billionaire and art collector Bill Koch.
La Gommeuse depicts a naked woman on the front and a previously unseen portrait on Picasso's friend Pere Manach, wearing an exotic headdress in with his head on the body of a female dancer, on the back.
The image remained hidden under the lining of the main painting for a century until it was uncovered during conservation work in 2000.
Picasso painted La Gommeuse after his friend Carlos Casagemas's suicide in 1901, and as he and Manach threw themselves into the debauchery of Paris life.
The painting will be the highlight of the Impressionist and Modern Art sale, which will also feature Nympheas by Monet, on 5 November.
Mr Shaw said described it as "two icons of art history from one of the greatest American collections ever assembled".