Golf Rules: What Happens When a Ball on the Green is Touched?

Question
If a player hits the green and the ball rolls near the hole and the next player's ball knocks the first ball of the green, where is the first ball played?

Answer
Dear Tom, thanks for the question. Hope you enjoyed Memorial weekend.  If player A's ball is hit and moved by player B's ball, then player A is to replace the ball as near to the spot as they know it to have been, and player B is to play their ball as it lies.  Occasionally you will see a tour player hurry up to the green and mark, just to avoid the possibility of his ball getting hit.  Good luck, thanks again for asking and remember...

Love the game,
skipper