Down the line describes a shot hit straight along the sideline. The ball travels parallel to the side boundary. It does not cross the court diagonally. This shot usually changes direction from a crosscourt rally. Because of the smaller margin, it carries more risk. Players must aim carefully to keep it in. However, it can surprise an opponent expecting a diagonal shot. For example, two players exchange crosscourt backhands. Suddenly, one drives the ball down the line. The opponent cannot recover in time. Down the line shots create sharp changes in angle and momentum.