There is a type of bicycle racing that they call a “sprint” match. A few competitors use fixed-gear bikes to race about 1,000 to 3,000 feet. Riding in your opponents slip-stream allows you to expend less effort, keeping you fresher for the end, so you can dash by him to the finish. At this short of a distance, you wouldn’t think it would matter much, but look how determined they can be.
More info on Wikipedia.