Edgar Degas, "The Fallen Jockey," 1896-98. Oil on canvas, 71" x 59."
In this picture Degas is making full use of the flattened, cut-and-paste space that his good friend Manet had mined some 30 years earlier. It certainly doesn't seem especially radical now, but placing things in the rectangle according to where one wanted them, and ignoring the spatial and perspectival inconsistencies that it created was still an eyebrow-raiser at the end of the 19th century.
And no, I'm not putting this picture up strictly for its horse racing content. As a matter of fact, when I went searching around the net for the picture's exact size, I found some of the most nonsensical analyses of the subject matter; that the horse represents the triumph of death and blah, blah, blah. The subject matter is quite secondary here - this picture is an arrangement of shapes and colors; representation teetering on the brink of abstraction which would arrive in about ten years.
Take a good look at the family resemblance between the Degas and this Ellsworth Kelly, painted about 65 years later: