There's always a battle going on somewhere between Sotheby's and Christie's for some piece of the art cake. But to get a sense of the biggest confrontation on the calendar, London is the place to be next weekend when the two auction houses exhibit highlights from their forthcoming New York sales of Impressionist, Modern (Monet to late Picasso) and Contemporary art (Rothko to today).

The most significant exhibit without a doubt is Picasso's eye-popping "Les Femmes d'Alger," 1955, based on a painting by Delacroix, that has a whopping $US140 million ($183 million) estimate from Christie's.