Reed's bid to claim the second leg of the calendar grand slam faltered with three bogeys in four holes around the turn, Koepka moving two ahead with a birdie on the 10th before scrambling to salvage a bogey on the next after firing his tee shot over the green and his second into a greenside bunker.
As Koepka emerged from a tightly bunched field on Sunday, Johnson simply couldn't keep pace. The exception was the Masters two years ago, when he tied for 21st.
Just behind: Tommy Fleetwood, who tied a US Open record with a final-round 63. And then he went 3-1 in his Ryder Cup debut at Hazeltine. Matt is on leave from work to play in the Open and a couple of other tournaments.
"Right now I feel like it's just shy but you never know".
"We didn't really speak too much, " Koepka said. If you screw up, you're gone.
Dustin Johnson had a four-stroke lead after 36 holes and was still in striking distance heading onto the back nine in the final round of the U.S. Open.
The USGA doesn't like to talk about scores, but that's the identity of this major.
But that's like asking why does a basketball game have to last for four quarters of 12 minutes each, as in both the NBA and PBA?
But Koepka, playing in the penultimate group with close friend Johnson, kept his early momentum going with a crucial putt for a bogey on the 11th to limit his losses.
And yet, DJ was nearly flawlessly ideal in the first two rounds with his tournament-leading 69-67.
After a lovely approach into the hard par-4 18th hole, Fleetwood gave himself about an eight footer to break the U.S. Open 18-hole scoring record.
"The course is gone", groused two-time major victor Zach Johnson. Floyd's victory also came at Shinnecock. "To play this tournament when there's nice weather, after a U.S. Open week, it's always nice to come back to this course".
"He's won every year he's been out here".
"I'm sure there's nobody happier for me than Dustin", Koepka said.
"Look, I don't mean disrespect to anybody", he said. The more you do it the more you get used to it.
Koepka has taken an unorthodox route to the top, having started his professional career in Europe rather than at home in the United States, but I think we are seeing the rewards of that.
"At the end of the day, I got within one of winning, when I was so far back at the start of the day", said Fleetwood, who was nine adrift through 54 holes.
Throughout the week, Koepka walked with a confident step.
Fleetwood now heads for the European Tour and the BMW International Open in Germany, which begins on Thursday. He blasted that out to 8 feet and made the putt to keep his lead at one shot.
Tommy Fleetwood was surprised when he shot 66 in Friday's second round. That kind of makes one wonder why Koepka isn't more of a household name. Strange, the last player to record the feat, did so in 1988 and 1989.
"Just be interested to see how things are tweaked tomorrow", Rose said. "I don't think I could have dreamed of this".
Those trophies could use some company.
"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 chief executive of the USGA and the man in charge of course setup.
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