Suddenly changing the pace by adding explosive speed in your feet movement is one of the most common, if not, the most used tactic in Singles in order to gain advantage and/or to score a point.
This tactic breaks the rhythm of the game, exploiting: a weak shot/return from your opponent, when the opponent is returning late to the base, when you anticipate successfully your opponent reply or just to break the mental pattern your opponent is getting used to.
This tactic is most often used in Singles, because you have more free space in the court to exploit. Nevertheless, it is also used in Doubles and Mixed doubles.
In this example, we have Lee Chong Wei and Lin Dan using this tactic effectively. You should focus on their feet movement.