It was the second day of our club's member-member tournament and my partner and I were playing a close match in our flight. We arrived at the 16th hole, a 175 yard downhill par 3 with the pin in the usual tournament pin placement in the back left of the green. I stepped up to the tee and could not get comfortable. I waggled a few times, stepped away, re-gripped and then stepped back to the ball. I tried to make a smooth swing and made contact. It felt good and the ball was on a nice trajectory. The ball was a bit left and seemed like it could go in the left bunker. On the descent it came back to the green and landed just inside the left edge at the top of the upper tier just before the slope to the small area where the pin was located. A good shot that I was happy with. At this point we could see that the ball was slowly moving down the slope. A good shot was getting a bit better. It was difficult to see if the ball had stopped to was still moving because it was moving so slowly. Our foursome started yelling for the ball to go in the cup. The foursome at the next tee box was even closer to the hole then us and they started yelling, the foursome behind us waiting for our tee box started yelling and then families in their yards overlooking the green starting yelling and then the ball disappeared!!!