A player plays what he believes to be his ball and hits it out of bounds. He plays another ball under Rule 27-1 and then discovers that the ball he hit out of bounds was a wrong ball and that his original ball is lying in bounds. What is the ruling?

In match play, the player loses the hole for playing a wrong ball (Rule 15-3a).

In stroke play, the ball the player hit out of bounds was a wrong ball, and the ball played under Rule 27-1 was a continuation of the play of that wrong ball.

The player incurred a penalty of two strokes under Rule 15-3b and he was obliged to hole out with his original ball.