Brooks Koepka has become the first player in three decades to win successive US Open titles as the American posted a one-shot victory at Shinnecock Hills in New York.
The 28-year-old fired a two-under-par 68 and with a one-over par total he won by one shot from Tommy Fleetwood, whose 63 equalled the championship's lowest round.
Koepka, who won the 2017 edition at Erin Hills by four shots with a tournament total 16-under par, became the first back-to-back US Open winner since Curtis Strange successfully defended his title in 1989.
Claiming his third victory on the US PGA Tour, world No.9 Koepka will pocket a winner's cheque of $US2.16 million ($A2.90 million).
"It sounds incredible," Koepka said of elevation to two-time major winner.
"To be honest with you, probably couldn't have dreamed of it in my wildest dreams. I'm at a loss for words right now; I couldn't be happier.
"We grinded our tail off this week to come back from seven-over (during the second round)."
The Florida native jumped out of the gates on Sunday with birdies at the second and third holes and never looked back, holding at least a share of the lead from there.
Koepka held his nerve in the face of bogeys at the sixth and 11th - where he drained a 13-foot bogey putt, before another dropped shot on his final hole.
"US Open just takes so much discipline; sometimes you feel like you are about to break mentally, but that's what I enjoy," he said.
He also withstood a furious charge from Englishman Fleetwood, who threw down the gauntlet with eight birdies and one bogey during a seven-under 63.
Fleetwood missed a short birdie putt at the last which would have given him the outright US Open record of 62.
World No.1 and 2016 winner Dustin Johnson birdied the 72nd hole but an even-par 70 gave him a three over total and solo third place, while Masters champion Patrick Reed (68) finished fourth at four over.
Aaron Baddeley finished as leading Australian, posting a 69 to earn a 12-over total and a share of 25th.
Compatriot Marc Leishman dropped four shots during a 74 that sank him to 15-over and he tied for 45th place.