Jeff Overton was disqualified midway through the third round of the Colonial on Saturday for illegally using a putting aid during play.
PGA Tour officials say Overton used an aid on a nearby practice green after playing the ninth hole while waiting to tee off at No. 10.
Going to the practice area is permissible during a round, but use of artificial or instructional devices isn't. The penalty is disqualification.
Rules official Mark Russell says it's unfortunate but that the rule is "clear as day."
Overton was 4 under for the tournament, seven strokes off the lead, when a PGA Tour official approached Overton after he teed off at the 11th hole. Russell says another player had asked officials about the use of the device.