The 36-hole leader had made 10 consecutive pars when he reached the par-5 11th hole where he hit his second shot into a bad lie in an un-raked portion of the sandy waste area. He then legally grounded his sand wedge behind the ball before taking two practice swings where he brushed a significant amount of sand way from behind the ball, ultimately improving his lie.

Host broadcaster, NBC Golf Channel, captured the entire incident on camera and replayed Reed’s indiscretion several times.

“He not only did it once he did it twice,” Dan Hicks said in commentary.

Expert commentator Paul Azinger added: “That is a way better lie than he had.”

Reed ended up bogeying the hole but birdied three of the last five holes to card an even-par 72. Before signing his card, rules officials asked Reed to explain the incident while viewing the Golf Channel footage. After being shown the replay and reviewing the incident for five minutes, Reed said it was something “I didn’t intentionally do.”

Reed, part of Tiger Woods’ US team to contest the Presidents Cup in Melbourne next week, was then formally penalised two strokes, which was added to his score on the 11th hole and changed his final score to a 74. He now heads into the final round three shots from the lead.

“You cannot remove or press down loose soil or sand, that’s the bottom line,” PGA Tour Vice President of Rules and Competitions Slugger White said.

Reed said his ball came to rest in a footprint and he took his practice swings further away from the ball than the video footage shows.

“It was in a pretty good footprint, but the footprint was a full footprint and I felt like … I mean, my club was that far behind the ball when I was actually taking the practice stroke, which I felt like I was taking it up and it was, obviously, it was hitting a little sand,” Reed said after being penalised. “I didn't feel it drag. But then whenever they brought it up to me and I saw it, it definitely did drag some of the sand. Because of that, it's considered a two-stroke penalty.

“I didn't feel like it really would have affected my lie. Every time I get in the bunker, I'm scared to even get my club close to it, and it was that far away. But whenever you do that, if it does hit the sand, just like if you're in a hazard area and you take a practice swing and it brushes grass and the grass breaks, it's a penalty.

“So, after seeing the video, it's a two-stroke penalty. I accept that. It wasn't because of any intent. I felt like I was far enough away.”

When Reed was asked if he felt the penalty was unfair he said: “Right, yes. I mean, it is, it is a big part, intent, but at the same time, when you only have one camera angle, that's all you can go off of, especially being how much sand's around here, how many footprints are there.

“It's a 50/50 battle whenever you're being assessed or anything like that, especially from that angle.

“I told him (Slugger White) it wasn't an intent and that I was far enough away from the ball, but because they didn't have another angle, they can't say anything either way. At the end of the day, because of where the camera angle was, they felt like it might have been improving the lie.”

Reed will start the final round at 10 under, three shots adrift of US Open Champion Gary Woodland. Sweden’s Henrik Stenson is one stroke behind Woodland at 12 under, with tournament host Tiger Woods, Justin Thomas and Spaniard Jon Rahm a further shot back and tied for third.