Masterworks by British contemporary art giants Francis Bacon and David Hockney will go under the hammer today in a £66 million bonanza.
Two Bacon works - a painting sold at his first commercial show in 1949 and a triptych portrait of his muse Isabel Rawsthorne - will be auctioned at Sotheby's in central London.
Contemporary art enthusiasts with deep pockets will also have the chance to bid for Hockney's colourful tribute to his home country, Double East Yorkshire, which has an estimated value of £3 million.
Other artworks by the likes of op art painter and drawer Bridget Riley and German photographer Andreas Gursky are among the total of 69 expected to go on sale with a combined estimated value in excess of £66 million.
Bacon's Head III is expected to go for between £5 million to £7 million, while the triptych has been valued at £10 million to 15 million.
Alex Branczik, head of Sotheby's contemporary art department, said: "Contemporary collectors in search of prize works, should find a great deal to excite them in our evening sale.
"It is very much an auction of historic 'firsts'. We are offering the first work that Francis Bacon ever sold, from his first show at a commercial gallery, in which for the first time he depicts the human form.
"We have the first David Hockney landscape to appear at auction since the hugely successful 2012 Royal Academy show; a 1964 Bridget Riley shown in the first ever exhibition of "Op Art" in New York in 1965 and Andreas Gursky's first Stock Exchange photograph of 1990 - part of an unparalleled collection of his iconic series of trading floor studies."