OAKMONT • The United States Golf Association (USGA) defended its management of a penalty controversy involving new champion Dustin Johnson in the final round of the US Open.

He was penalised a stroke on Sunday after the USGA deemed the player was responsible for making his ball move on the fifth green, even though a walking official with the American's group absolved the player of any wrongdoing.

When Johnson reached the 12th tee, Jeff Hall, the USGA's managing director of rules and competition, visited the 31-year-old to inform him that he could be assessed a penalty and that the matter would be discussed after the round.

"We were concerned about what we saw and felt obligated to have a conversation with Dustin about it," Hall said. "We told him that what we saw was a concern but we also asked him a couple of questions."

Hall asked Johnson if there was something else that could have caused the ball to move, but the player was adamant he had not grounded his club and did not cause his ball to move.

However, Hall and his fellow committee members felt Johnson's putter was grounded near the ball as he took his practice swings.

Fortunately for Johnson, the penalty only served to reduce his margin of victory to three shots.

"I didn't think I did anything to cause the ball to move, but at the end of the day, it didn't affect what happened," he said. "So it doesn't bother me at all."

The USGA was criticised for waiting until the 12th tee to inform Johnson that there might be a penalty assessed.

"This is ridiculous... No penalty whatsoever for DJ. Let the guy play without this crap in his head. Amateur hour from @USGA," tweeted world No. 3 Rory McIlroy.

PGA Tour pro Brandt Snedeker tweeted: "Hey @USGA, it's impossible for DJ to cause the ball to move backwards!!!!!!! #commonsense."

Thomas Pagel, the USGA's top rules official, was unapologetic, saying a number of factors went into the decision to dock Johnson a stroke, including the steepness of the Oakmont greens and the time that elapsed between the time the player put his putter behind the ball and the time the ball moved.

"It's not going to be 100 per cent clear, yes, the player caused the ball to move, but that's not the standard we're dealing with," Pagel said, explaining that it need only be more likely than not that the player caused the ball to move for a penalty to be incurred.

REUTERS, AGENCE FRANCE-PRESSE