Francis Bacon's Study for the Head of Isabella Rawsthorne and George Dyer (1967) has sold for £12.1m ($19.1m) at Christie's London.
The work provided the headline lot of the June 30 contemporary art evening sale.
Francis Bacon's work is increasingly sought after following a world record sale in 2014
The lot is one of only 10 diptychs Bacon painted over the course of his lifetime. Rawsthorne and Dyer were two of the most important people in his life, making this a highly important piece in his canon.
Two Men Working in a Field (1971), another work by Bacon, sold for £10.7m ($16.8m).
One of the best results of the night was for Chris Ofili's Holy Virgin Mary, which sold for an artist record of £2.8m ($4.3m).
The work received major press in 1999, when New York mayor Rudolph Guiliani described it as "sick" after seeing it in an exhibition of British artists in the Brooklyn Museum.
It's partly painted in elephant dung.
Edmond Francey, Christie's head of post war and contemporary art in London, commented: "Tonight we saw the culmination of a historic season for Christie's.
"The depth and breadth of activity was seen by the broad geography of not only bidders and material. This was an example of Christie's doing what it does best, with consistent results in comparison to last year."
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