The R&A and USGA have revised a rule which was only introduced in January after two controversial incidents on either side of the Atlantic.

China's Li Haotong was penalised two shots on the 72nd hole of the European Tour's Omega Dubai Desert Classic because his caddie was on a direct

line behind the ball when he began to take his stance on the green.

That was in breach of rule 10.2b(4), one of a number amended at the start of

2019, and meant the defending champion dropped from a tie from third to a tie for 12th, costing him more than 80,000 euro.

Five days later American Denny McCarthy was penalised for the same offence in the Waste Management Phoenix Open on the PGA Tour, although that penalty was swiftly rescinded.

A joint statement from the R&A and USGA on Wednesday read: "The purpose of Rule 10.2 is to reinforce the fundamental challenge of making a stroke and to limit the advice and other help a player may receive during a round.

"Rule 10.2b(4) ensures that aiming at the intended target is a challenge that the player must overcome alone. It states: "When a player begins taking a stance for the stroke and until the stroke is made, the player's caddie must not deliberately stand in a location on or close to the player's line of play behind the ball for any reason. If the player takes a stance in breach of this Rule, he or she cannot avoid penalty by backing away.

"Exception - Ball on Putting Green: When the player's ball is on the putting green, there is no penalty under this Rule if the player backs away from the stance and does not begin to take the stance again until after the caddie has moved out of that location.

"The two clarifications provided today can be summarised as follows:

"Meaning of "Begins Taking a Stance for the Stroke": If a player backs away from a stance, the player is not considered to have begun a "stance for the stroke". Therefore, a player can now back away from his or her stance anywhere on the course and avoid a breach of Rule 10.2b(4) if the caddie had been standing in a location behind the ball.

"Examples of When a Caddie is Not "Deliberately" Standing Behind the Ball When a Player Begins Taking Stance for Stroke: As written, the Rule does not apply if a caddie is not deliberately standing behind a player.

"It is clarified that the term "deliberately" requires a caddie to be aware that 1) the player is beginning to take a stance for the stroke to be played and 2) he or she (the caddie) is standing on or close to an extension of the line of play behind the ball."

David Rickman, executive director of governance at the R&A, said: "These clarifications are designed to improve the operation of the Rule and give the players more opportunity to avoid a breach while remaining true to the purpose of the Rule.

"We appreciate that this requires some players and caddies to make an adjustment, but we believe there is widespread acceptance that it is for the player alone to line up a shot."