No, there is no penalty for a player pressing down a ball-marker, whether it is on his own line of putt, a fellow competitor’s or an opponent’s. Decision 20-1/15.5 relates to changing the lie of a player’ own line of putt;

Q. A player marks the position of his ball, and as a result of the act of marking, there is a change in the lie of the ball. Is the player required to restore the lie he had before marking the position of the ball?

A. No. The act of placing a marker may result in some change in the lie of the ball, for example, from grass being depressed by the weight of the marker, or grains of sand being moved in the placement or removal of a marker. Such occurrences may improve or worsen the lie of the ball, and the player must accept the result.

If the player attempted to restore the lie under these circumstances, or if the lie was improved from actions which exceeded what was necessary to the process of marking, he would be subject to penalty under Rule 13-2.

Also, Decision 20-1/6.5 states that there is no penalty if a player’s ball-marker on the green is pressed down by an opponent as Rule 18-3b does not apply to ball-markers.

Regards,

BarryR
For GolfSwingSecretsRevealed.com

Would he not of infringed a rule buy pressing down the marker thus improving the line of his opponents putt?

Instead should he not have moved the marker to the side one putter head length or more?

As I believe you can not press down on the line except to repair pitch marks.

Which one would he be ?