Koepka was speechless when reminded he had won four majors from eight starts.
«I like the way that sounds,» said Koepka, who missed the 2018 Masters with a wrist injury. «Phenomenal. It’s been a hell of a run.»
Koepka’s major haul equals Rory McIlroy while it surpasses Jordan Spieth (three) — previously seen as the two most dominant golfers since Woods’ prime.
Florida native Koepka began Sunday at Bethpage with a lead that history suggested could not be lost.
His seven-shot advantage after 54 holes was the largest in PGA Championship history and was one that had never failed to produce a win at the majors, nor on the US PGA Tour.
But the wheels fell off spectacularly when four straight bogeys from the 11th hole allowed Johnson to pull within one stroke when he birdied the 15th.
With Koepka on pace to record the worst choke at the majors, the boisterous New York fans chanted «DJ!» in support of a barnstorming Johnson.
«They’re New York fans; what do you expect when you’re half choking it away? I deserved it,» Koepka joked.
However, two late bogeys from Johnson allowed Koepka to bogey the 17th — and save a miraculous par on the 18th — to seal victory.
Koepka shot a four-over 74 and at eight-under-par (272) he finished two strokes ahead of Johnson (69).
His 74 was the highest final round by a PGA champion in 15 years.
«Today was definitely the most satisfying out of all (four) for how stressful that round was,» Koepka said.
Koepka became the first player since Woods (1999-2001) to win four US-based majors from six starts.
He also joined Woods (1999-2000 and 2006-2007) as the only players to win back-to-back PGA Championships since it moved to stroke play in 1958.
Six-time major winner Nick Faldo admitted it was hard to argue Koepka had established a new world order among golf’s four biggest events.
«50 per cent? That is some seriously unbelievable dominance,» Faldo said.
Left in Koepka’s wake was Spieth (71), who earned his first top-10 on the PGA Tour since July last year to share third at two under with Patrick Cantlay (71) and England’s Matt Wallace (72).
Adam Scott shot 74 to share eighth at one over and lead the Australians, while Jason Day (72) shared 23rd at four over, Cameron Smith (74) was 11 over and Lucas Herbert (75) was 12 over.
Scott is enjoying a major championship resurgence, but struggled to enjoy it after a lacklustre final round.
For a fourth straight major, Scott was in the mix but failed to find another gear in search of a long-awaited second victory to go with his historic 2013 Masters win.
«It’s just hopeless and it’s not going to win many tournaments,» Scott said of his final round.
«I would have liked to get more out this week; there was some good stuff but it’s frustrating to have an average result again.»
Fellow Australian Jason Day, the 2015 PGA champion, closed with a 72 to drop to four over and tied for 23rd.
Cameron Smith’s 74 gave him an 11-over total and Lucas Herbert (75) finished a stroke further behind.
BROOKS KOEPKA’S PGA CHAMPIONSHIP TRIUMPH BY THE NUMBERS
- Secures his fourth major victory, to go with the 2017 and 2018 US Open titles as well as the 2018 PGA Championship
- Becomes the first player in history to win the US Open and US PGA Championship back-to-back in a career
- Joins Tiger Woods (1999-2000 and 2006-2007) as the only players to win back-to-back PGA Championships since it moved to stroke play in 1958
- Becomes the first male golfer in history to hold two different majors back-to-back at the same time, and the first to win his first four majors in less than two years
- Becomes the first player since Hal Sutton in 1983 to win the PGA Championship in wire-to-wire fashion
- Becomes the only player under the age of 30 to have four major wins
- Joins Rory McIlroy as the only player under age 40 with at least four majors
- Moves to world No.1 again, his fourth stint at the top of the rankings
- Wins $US1.98 million ($A2.86m) winner’s share of the $US11 million PGA purse
- Koepka’s four-over score was the highest final round in relation to par by a winner of a major since Vijay Singh shot 76 to win the 2004 PGA Championship (Singh won in a play-off).