Leave one far behind, as in a race or competition. For example, This marketing strategy will leave the others in the dust. This metaphoric colloquialism alludes to the dust raised by a fast-moving horse or vehicle.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.