<P> Instead the player who was further away from the hole had to attempt to slice or draw his putt around the obstacle ball . Sometimes a player would even attempt to chip his ball over the opponent's ball into the cup . </P> <P> If the player failed, even hitting their opponent's ball, his next shot would have to be played from where his ball now lay . If contact happened, the player's opponent, when it was his turn to play, had the choice to take his putt from his ball's original position or its new lie . </P> <P> Likewise if the player's ball knocked the obstructing ball into the cup, his opponent was considered to have holed out on the previous shot . For example, a ball lying 3 on the green is knocked into the hole by another ball--in this instance the score for the player whose ball was knocked into the hole would be 3 . </P> <P> In 1920, the United States Golf Association tested a modified stymie rule for one year, allowing a stymied player to concede the opponent's next putt . The next change to the stymie rule came in 1938, when the USGA began a two - year trial in which an obstructing ball within 6 inches (15 cm) of the hole could be moved regardless of the distance between the balls . The USGA made this rule permanent in 1941 . However, during this time, the Royal & Ancient Golf Club of St Andrews never modified the stymie rule . </P>

When did they start marking golf balls on the green