Francis Bacon's triptych Three Studies for a Portrait of George Dyer has sold for £26.6m ($45.6m) at Sotheby's London.
The lot crossed the block on June 30 as part of the Contemporary Art Evening Auction.
Oliver Barker of Sotheby's told the Guardian prior to the sale: "Dyer was one of the great loves of Bacon's life and this is the first time a triptych of him has ever come to market.
"The first time I saw it was like uncovering a long lost jewel".
The two men met when Bacon caught Dyer, a petty criminal with a troubled past, burgling his home in 1964 - the year that this triptych was painted.
Their relationship lasted until 1971 when Dyer, now severely alcoholic, overdosed on barbiturates in a Paris hotel room.
Bacon would learn of his suicide at the opening night of his retrospective at the Grand Palais, an event he would later document in his series of Black Triptychs (1972-1974).
In November 2013, Bacon's Three Studies for a Portrait of Lucian Freud set a new world record for a work of art at auction when it sold for $142.4m at Christie's New York.
In May this year, a full size triptych of his friend John Edwards auctioned for $80.8m at Christie's New York.
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