By riding behind the 'lead out' rider, the second rider reduces the aerodynamic drag felt. Just before the finish, the trailing rider pulls out of the slipstream, and aided by fresher legs, may be able to overtake the opponent before the line. To prevent this, the leading rider may choose to accelerate quickly before the last lap, hoping to catch their opponent off guard and establish a large enough gap to negate the aerodynamic effect or to keep the speed high enough to prevent their opponent from completing a pass.