The American carded a closing 69 at Oakmont to finish four under par, but only after being given a one-shot penalty following an incident which left players, officials and spectators unsure of his score with just seven holes to play.
Johnson had overturned a four-shot deficit to seemingly move two shots clear of the field before being told on the 12th tee that officials would review an incident on his fifth hole after the round.
The 31-year-old had seen his ball move fractionally as he lined up a putt, but called in the referee walking with his group and was initially cleared of any wrongdoing before holing out for par.
Fortunately for both Johnson and USGA officials, the challenge of Shane Lowry, Scott Piercy and Sergio Garcia faded in the closing stages and Johnson ensured any penalty would not matter with a stunning birdie on the 18th.
But many of the world’s leading players, including Rory McIlroy and Jordan Spieth, took to Twitter to express their dissatisfaction with the situation, and the USGA has now admitted it regrets the distraction caused to the players.
“Upon reflection, we regret the distraction caused by our decision to wait until the end of the round to decide on the ruling,” read a statement.
“It is normal for rulings based on video evidence to await the end of a round, when the matter can be discussed with the player before the score card is returned.
“While our focus on getting the ruling correct was appropriate, we created uncertainty about where players stood on the leaderboard after we informed Dustin on the 12th tee that his actions on the fifth green might lead to a penalty.
“This created unnecessary ambiguity for Dustin and the other players, as well as spectators on-site, and those watching and listening on television and digital channels.”
As for the penalty itself, rule 18-2/0.5 states: “If the weight of evidence indicates that it is more likely than not that the player caused the ball to move, even though that conclusion is not free from doubt, the player incurs a one-stroke penalty.”
The statement continued: “During any competition, the priority for Rules officials is to make the correct ruling for the protection of the player(s) involved and the entire field.
“In applying Rule 18-2, which deals with a ball at rest that moves, officials consider all the relevant evidence – including the player’s actions, the time between those actions and the movement of the ball, the lie of the ball, and course and weather conditions. If that evidence, considered together, shows that it is more likely than not that the player’s actions caused the ball to move, the player incurs a one-stroke penalty.
“Officials use this ‘more likely than not’ standard because it is not always apparent what caused the ball to move. Such situations require a review of the evidence, with Decision 18-2/0.5 providing guidance on how the evidence should be weighed.
“Our officials reviewed the video of Dustin on the fifth green and determined that based on the weight of the evidence, it was more likely than not that Dustin caused his ball to move.
“Dustin’s putter contacted the ground at the side of the ball, and almost immediately after, the ball moved.”