Explainer: Here's what you can and can't do on the green, and why those rules exist in the first place
Sergio Garcia did not tap down spike marks on his putting line on Thursday at the HSBC Championship in Abu Dhabi. But what if he had? And what's the big deal with tapping down spike marks, anyway? To answer the first question: It's a violation of Rule 16-1a and comes with a two-shot penalty in stroke play (loss of hole in match play).
The tournament committee could have also disqualified Garcia if they felt he had gained a significant advantage by tapping down the spike marks. That would be considered a serious breach of the rules. The European Tour's Simon Dyson was disqualified at the BMW Masters in October after tapping down spike marks.
And here's what you can't do: