Rory McIlroy claimed the biggest PGA Championship win when he triumphed by eight shots at Kiawah Island in 2012, while the largest winning margin in a major is 15 shots by Tiger Woods in the 2000 US Open at Pebble Beach. "Obviously not a spot where you can go, but hit a great chip and a good putt, and you know, made a five", said Johnson. And I don't know how my ball went over the green there.
On a day when the winds blew steadily at 23 miles per hour and gusted even higher, Johnson was the only one who entered the final round in the top 25 to post a negative number, and the only one in the field to shoot in the 60s in all four rounds.
Johnson, meanwhile, found the fairway then flew the green with a five-iron from 192 yards into the wind to leave himself with an incredibly hard chip shot.
Koepka is almost halfway there after his two-shot victory over fellow American Dustin Johnson on Sunday, when he recovered from four consecutive bogeys to limp across the line thankful he had started the day with a seven-shot buffer.
That margin of victory was even more notable after he played the first nine holes of his first round in four-over 40, before coming home in six-under 30 for a round of 70 which left him three off the lead. He had a 5-iron in his hand and thought about going back for a 4-iron; he stuck with the 5 - and flew the green with it.
Johnson was one of just 10 players to break par Sunday, his score of 69 bested by just two players. His major charge would seem to suggest he is the true heir apparent to Woods, the Masters champion he beat by 17 shots after two rounds. Scottish golfer Willie Anderson won the U.S. Open in 1903, 1904 and 1905. Johnson could and should be a multiple major victor. But this victory will put Koepka in exclusive company. When he got to that total in February at the WGC-Mexico Championship, he was the first to cross that threshold since Davis Love III in 2008.
Koepka was six when Woods won the first of his 15 majors at the Masters in 1997, and he grew up with his countryman's notion that golfers should be athletes.
The 29-year-old retained the Wanamaker Trophy to become the first player to win his first four majors inside two years and he is confident he has more to offer.
But his major record is pocked with near misses and should-have-beens. He has 10 top-10s in his past 16 major starts. The misfired 2-iron on the 14th hole of the final round at Royal St. George's a year later ended up in the trash bin, but he didn't sulk for long.
He established his dominance with a six-under 65 to lead by three after 18 holes and was six clear at halfway following a 66 in the second round.
Another 69 left him in a four-way tie for second heading into the final day, when Koepka was so far ahead of the pack that it looked like the only competition would be for the best of the rest.
Even the 72nd-hole three-putt - a 12-footer for eagle would have won, a 3-footer for birdie would have tied - at the 2015 U.S. Open was short-lived.
But despite the latest near-miss, the former U.S. Open victor walked away from the massive Bethpage Black layout, where he was the only person in the 156-player field, to break par in all four rounds.
"It's very humbling. You see the appreciation that everybody has for those guys and what they've accomplished in their careers and how great their careers have been". Cruising through 54 holes, suddenly the game became hard.
The 29-year-old American has long-been a strong favourite to wrap up his fourth major success and, having already broken a number of records this week, he can rewrite the record books once again on Sunday afternoon in NY. Ahead of him, Johnson made birdie on the 15th - the toughest hole at Bethpage Black all week - and the lead was down to one. I'm still in a state of shock.
WORLD RANKINGS: Koepka moved to No. 1 in the world with the victory, supplanting Johnson.
Koepka held it together at the most crucial moment. And that has to sting.