Brooks Koepka has already showed he could win a US Open when the scoring was easy, conquering the field at Erin Hills in 2017 with a winning 16-under score. But could he claim this major title on a “traditional” Open course, where aggressive play could leave you shaking your head and mumbling to yourself?

The 28-year-old proved he’s got that gear, too, grinding out a two-under 68 at vaunted Shinnecock Hills on Sunday to become the first player to win the USGA’s marquee championship in back-to-back years since Curtis Strange in 1988-’89 and just the seventh ever.

“It hasn’t sunk in yet,” Koepka said. “I don’t think I could have dreamt this, to go back to back. It’s truly special.”

To win with an one-over-par 281 total, Koepka had to hold off his good friend Dustin Johnson, who he shared the lead with at three-over par entering the final round along with Daniel Berger and Tony Finau. None of the trio, however, were able to put much pressure on the defending champion, DJ shooting an even-par 70 to finish in third, Finau posting a 72 to finish fifth and Berger shooting a 73 to finish tied for sixth.

Instead, it was a player who had posted a score nearly three hours earlier who was lurking in Koepka’s mind. Tommy Fleetwood became just the sixth player to shoot a 63 in the US Open on Sunday, the Englishman making eight birdies to one bogey to get into the clubhouse at two-over 282. But a missed seven-footer for birdie on the 18th hole that would have made him the first to post 62 became the stroke that kept him out of a playoff.

“I honestly never really felt I was out of it,” Fleetwood said. “I just needed a good start.’

And that’s what he got, making birdies on four of his first seven holes to pick up momentum. After a bogey on the ninth hole, Fleetwood rode a hot putter to four straight birdies on the 12th to 15th holes.

Koepka was on the eighth hole when Fleetwood finished, sitting at one-over par and knowing he had to stay there or go lower to avoid a playoff with the Englishman. Koepka then played the final 10 holes in even par, making several clutch par saves, and then a breathing-room birdie on the par-5 16th that allowed him to bogey the last hole but still win by one stroke and claim the $US2.16 million first prize.

That there was a 63 out there, or a winning 67, showed that the golfers didn’t have to play scared on Sunday at Shinnecock. With the third-round scoring average winding up at 75.33, USGA officials couldn’t have a repeat of Saturday’s madness, least they have a repeat of the Sunday nightmare in 2004. And so they placed several hole locations towards the centre of the greens, willing to have a set up that yields birdies rather than bellyaching.

The unexpected final twosome of Finau and Berger couldn’t take advantage of opportunities they created with their Saturday 66s. Berger bogeyed three of his first six holes. Finau struggled early only to find his swing midway through the round but it was too little too late.

Most surprisingly, Johnson couldn’t capitalise on a day where scores could be had. The World No.1 had held a share or the outright lead for the first three rounds at Shinnecock Hills but didn’t have his putter working on Sunday, missing four birdie and par putts from inside seven feet.

Another Major winner also tried to have something to say about the outcome on Sunday. Masters champion Patrick Reed birdied five of his first seven holes to grab a share of the lead at one point with Koepka. But a trio of bogeys on the ninth, 11th and 12th holes put an end to the dream of a calendar year Grand Slam, Reed finishing with a 68 to finish three-strokes behind Koepka in solo fourth place.

Making Koepka’s repeat win all the more impressive was the fact that he missed three months this season – including the Masters – while trying to recover from a tendon injury in his wrist. It was only at the Zurich Classic in April that he returned to action. In five starts he made four cuts, including a runner-up finish at the Fort Worth Invitational.

“I don’t feel like there is anybody out there with more confidence than me,” Koepka said during the week at Shinnecock. It seemed like a fairly large boast, but he proved it was more than hyperbole. It was his winning formula.

Aaron Baddeley was the pick of the Australians, firing a final-round 69 to finish 12-over and in a tie for 25th.