A painting by Francis Bacon of his friend and fellow artist Lucian Freud has sold at auction for £23m ($37m) - three times the pre-sale estimate.
The triptych, Three Studies For A Portrait Of Lucian Freud, went to an anonymous buyer at Sotheby's in London.
Cheyenne Westphal, from Sotheby's, said it was "an artwork that radiates 'wall-power'".
The sale also saw a Salvador Dali painting reach £13.5m - a new record for any Surrealist work at auction.
The price for Portrait de Paul Eluard smashes the previous record for Dali of £4.1m, which was set in London just 24 hours earlier.
Bacon and Freud met in 1945 and became close companions, painting each other on a number of occasions.
Three Studies For A Portrait Of Lucian Freud has been kept in private since shortly after its completion in 1965.
It was expected to sell for between £7m and £9m, but when it came up for auction on Thursday the price was driven up by more than 10 competing bidders from four continents.
It eventually went for a £23,001,250, including the buyer's premium.
Ms Westphal, chairman of Contemporary Art Europe at Sotheby's, said: "This striking painting has everything a collector in the current market is looking for.
"It is an artwork that radiates 'wall-power' with its brilliant colour and dramatic brushstrokes.
"It narrates one of the most impressive artistic relationships of the 20th Century between two titans of British art and is desirably fresh to the market having remained in the same collection for almost half a century."