A nude portrait by Francis Bacon, of the Soho model Henrietta Moraes, has sold for £21m at Christie's in London.
The painting had been in the hands of a private collector and has not been seen in public for 15 years.
The amount was one of the highest fetched by a work of post-war contemporary art at Christie's.
The current record for a Bacon was set at Sotheby's in New York in May 2008, when one of the Irish-born artist's Triptychs sold for $86.3m (£55m).
Bacon painted more than a dozen portraits of Moraes, a familar Soho denizen who also posed for Lucien Freud.
Francis Outred, of Christie's, said the painting sold this week was "one of the most seductive and sexually-charged" he had ever encountered.
The £21.3m price - paid by an anonymous bidder - was more than £1m above the auction house's top estimate.
The same event also saw a Lucien Freud etching sold for £145,250 - the highest amount that one of the late artist's prints has ever fetched at auction.