Rule 25-2:

A ball embedded in its own pitch-mark in the ground in any closely-mown area through the green may be lifted, cleaned and dropped, without penalty, as near as possible to the spot where it lay but not nearer the hole. The ball when dropped must first strike a part of the course through the green. "Closely-mown area" means any area of the course, including paths through the rough, cut to fairway height or less.