DrewSnapper

So i was playing a practice round and i hit my ball in the rough and the Greenkeeper started cutting that area of grass as i left the tee and when i was walking up the hole he drove straight over my ball and it shot straight across the fairway and when i saw it, it was sliced halfway through the centre of the ball. It just got me thinking what the ruling is if that happened in competition. If anyone knows what the correct ruling is could you tell me. Thanks