A fly fastbreak (also known as a one out fastbreak) is a basketball move in which after a shot is attempted, the player who is guarding the shooter does not box out or rebound, but runs down the court looking for a pass from a rebounding team mate for a quick score.
The coach designates a certain guard or guards to carry out the Fly fastbreak. This is often the guard that defends the opponents shooting guard. When the designated opposing guard makes an attempted shot. The defending guard (refer to as 'Fly') will contest the shot, but then sprints down the court to the other teams key. When the defending team obtains the rebound, or has to inbound the ball (after a made basket), they throw the ball into the other team's key, knowing that there is a 'Fly' waiting to catch the ball and score.