Once you determine that the ball has moved, you then need to determine what caused it to move. The cause of the movement will determine whether or not you need to replace the ball or play the ball as it lies from its new position. There are only four possible causes in the Rules that could move the ball:

• Natural forces, like wind, water or the forces of gravity;
• You, the player (including your caddie, or partner and partner’s caddie in partner forms of play);
• Your opponent (including their caddie); or
• An outside influence (such as another player in stroke play, animal or spectator).

When figuring out which of these four caused the ball to move, you again apply the known or virtually certain standard. In this case, there is a default – if it is not known or virtually certain that you, your opponent or an outside influence caused the ball to move, then the Rules default to natural forces and treat the situation as if natural forces caused the ball to move.

There are also two instances where you will replace your ball regardless of what causes it to move:

• When the ball is on the putting green and has already been lifted and replaced, you must replace the ball regardless of what causes the movement.
• When you’ve taken relief and after coming to rest natural forces cause the ball to move to a different area of the course, you must replace the ball on its original spot (but not if it moves somewhere else in the same area of the course).