Johnson, four-under and leading by four heading into the round, was in trouble early with his first double bogey of the week at the par three second.
SOUTHAMPTON, N.Y. -No one was happy about the conditions that set up the final day of the U.S. Open. Nowhere was that more evident than on the par-3 11th.
He'd follow up a two-putt bogey, which was all he needed to take home the win. Meanwhile, Johnson missed a four-footer for par, unable to close the gap.
Fleetwood was one shot behind when he finished, and Koepka still had 11 holes to play as Shinnecock Hills began to get crisp under another sunny sky. But only Koepka went low, and none of the other three co-leaders could mount a serious challenge.
"It was a tale of two golf courses, and no doubt, we would admit, well-executed shots were not only not regarded, but were punished, " said Mike Davis, the USGA's executive director and the man in charge of course setup.
Berger and Finau beat the worst of the conditions, finishing before the leaders had even teed off.
"I was saying to the guys out there, from yesterday afternoon, I played late, and it was calm and obviously from the rain previous in the day, we were struggling to get putts to the hole yesterday afternoon". But, alongside his obvious raw power, the 28 year old was nerveless on the greens and deserved to join Ben Hogan (1950-51) and Curtis Strange (1988-89) as the only players in the last 75 years to complete a successful defence.
But the 63 is for certain, and Fleetwood is now in the record books.
For a brief moment, it appeared reigning Masters champion Patrick Reed might haul his "Captain America" nickname out of the Ryder Cup and into a major. He was 7 over for the championship through seven holes of the second round when he ran off six birdies for a 66 to get back in the game.
Finau finished the third round hoping he could enter Sunday within six strokes of the lead; more than that would be too far back, he figured.
The U.S. Open won't be so tough on Sunday with the trophy at stake.
But Koepka steadied himself and ground his way home in the traditional style of a U.S. Open victor, making par on six of the last seven holes and birdieing the par-5 15th to give himself some breathing room.