The course was very playable in the morning, as attested by matching rounds of 66 by Daniel Berger and Tony Finau, but it was a different beast in the afternoon after the winds and low humidity baked the greens to a crisp. Two guys who began the day 11 shots behind Johnson.
Tommy Fleetwood was surprised when he shot 66 in Friday's second round.
The scoring average of 75.33 was the highest for a third round in the US Open since 2000 at Pebble Beach.
Kiradech Aphibarnrat had the only other round under par. Koepka made only two birdies in a hard-earned round of 72, leaving him in position to become the first back-to-back victor of the US Open since Curtis Strange in 1989.
"I had a chance to make history but I wouldn't do anything differently", he said.
Shinnecock Hills is one of the toughest challenges in golf. Despite two missed cuts in four British Open starts, it would seem unwise to sleep on his chances next month at Carnoustie.
It was a U.S. Open that produced an obviously stacked leaderboard, with an outcome in doubt until the final few holes, a record-tying Sunday scoring performance (Tommy Fleetwood's 63 that enabled or forced him, depending on perspective, to sit in the hospitality tent with the clubhouse lead for hours), and an historic victor in Koepka, the rising American star who became only the third person to win consecutive U.S. Open championships since World War 2, and the whole thing was contested on one of the best classic courses in the United States.
"A little bit more grass (on the greens) would have been nice in the afternoon". The USGA conceded the course was over the top and pledged to get it right for the final round. He finished at 2 over and stood one shot out of the lead as he walked off the course. He's one of the best players in the world. I thought we could be on the edge, but we've surpassed it, ' Johnson told Sky Sports. Phil Mickelson intentionally broke a rule on the 13th when he trotted to his ball rolling by the cup and swatted it with his putter as the ball was still moving.
Mickelson had a one-stroke lead heading into the 18th hole at Winged Foot. I feel for the membership, because I know many of them. I hit one on the par five, number five, that I landed 10 feet from the hole, and it ended up 50 yards away.
Rose, whose victory at Merion in 2013 was the last time a tournament on the PGA Tour was won with an over-par total, was left to regret two bogeys in the last three holes but said: "I love my position". The whole family went to Idaho the following day, and he says Johnson played golf with them for 20 straight days. "Look, I don't mean disrespect by anybody".
Gretzky was at Oakmont two years ago but had to leave before the final round when Johnson won the U.S. Open.
Despite all the difficulties, Johnson steadied himself to arrive at the 18th tee with a one-stroke lead.
With the two-stroke penalty Mickelson took a sextuple bogey 10.
For all Dustin Johnson's power and athleticism, Wayne Gretzky believes one of his greatest assets is his attitude.