Although the game has existed for a long time, its popularity has risen in recent years as a result of concerns that nine-ball has suffered as a result of flaws in its fundamental structure (particularly the ease with which players can often make balls from the break). The World Pool-Billiard Association (WPA) World Standardized Rules for 10-ball are very similar to those for nine-ball, but with key changes to ensure the difficulty of the game and its marketability as an alternative to nine-ball.