For the big-fish bidders at the impressionist and modern sales, the June auctions are the high point of the calendar. This week’s sales, however, promise not just record prices but significant surprises.

Two years ago, top lots in the impressionist and modern art sales were familiar brands: the Monets, Picassos and Van Goghs. More recently, bolder, brasher artworks by lesser-known artists have been netting record prices and, this summer, German expressionists and Italian futurists will be among the most sought-after catches.