And nothing could stop Koepka.
Tied for the lead with six holes to play, Koepka made an 8-foot par putt on the 13th hole. As Brian Harman began to fade, Koepka poured it on with birdies over the next three holes, lightly pumping his fist after each one.
His reaction was subdued, just like his close friend and last year's U.S. Open champion, Dustin Johnson.
It capped quite a journey for the 27-year-old Floridian.
Without a card on any tour when Koepka got out of Florida State, he filled his passport with stamps from the most unlikely outposts in golf while playing the minor leagues on the European Tour Kazakhstan and Kenya, Portugal and India and throughout Europe.
It was at the U.S. Open three years ago when Koepka tied for fourth that helped earn a PGA Tour card, and he powered his way from obscurity to his first Ryder Cup team last fall and now a major champion.
Harman's chances ended with two straight bogeys, and a bogey on the par-5 18th hole gave him a 72 and a tie for second with Hideki Matsuyama of Japan, who closed with a 66. Matsuyama didn't need to stick around very long. Koepka simply couldn't miss.
He became the seventh straight first-time winner of a major championship, and it was the first time since 1998-2000 that Americans won their national championship three straight years.
R Brooks Koepka makes three straight birdies on the back nine at Erin Hills (Wis.) and closes with a 5-under 67 for his first major title.
• Koepka totals 272 and ties Rory McIlroy's U.S. Open record by finishing at 16 under par.
• Hideki Matsuyama and Brian Harman tie for second place, four strokes back.
Inside • Utahn Daniel Summerhays shoots 81 in the final round and finishes 65th. > B3