US golfer becomes 15th different winner of tournament in 15 years after overhauling big-name pack.
Webb Simpson battles back to win US Open
The 26-year-old from North Carolina, in just his second US Open, battled back from two early bogeys to grab four birdies in five holes from the sixth and then parred his way down the rest of the back nine for a gripping win.
Simpson closed with a 68 and a one-over total of 281, one stroke clear of countryman Michael Thompson (67) and Northern Ireland's Graeme McDowell (73).
A further stroke back in a five-way tie for fourth place were Americans Jim Furyk (74) David Toms (68), Jason Dufner (70) and John Peterson (70) along with Ireland's Padraig Harrington (68).
Simpson was the ninth straight first time winner in the majors and he was the 15th different winner in the last 15, underlining once again the current strength-in-depth of world golf.
It was day when birdies were rare and survival was the order of the day as a cold mist and spotty rain drifted in from the adjacent Pacific Ocean to compound the difficulties of the exacting Lake Course layout.
Former winners Furyk and McDowell started the day holding the joint lead - the only men to be under par at one-under 209.
First blood went to Furyk as he took the solo lead after McDowell bogeyed the third and when the Ulsterman had a second bogey at the fifth, the Ryder Cup stalwart had a two-stroke lead.
He missed a 10 footer at the eighth that would have nudged him three strokes ahead and then, in his rear-view mirror, he saw a trio of young American countrymen - Simpson, Thompson and Peterson - making a charge at him.
First round leader Thompson set the early clubhouse standard with a 67 for a two-over total of 282 and sat back to watch if anyone could match him.
Surprisingly, Furyk started to unwind.
He bogeyed the 13th and then flung his club away in disgust after hitting a snap hook off the tee on the par-five 16th.
He salvaged a bogey from out of the trees, but up ahead Simpson negotiated a tricky chip from deep greenside rough to save par at the last and that, coupled with the bogey for Furyk, left him one clear.
Furyk needed one birdie on the last two holes to force a playoff with McDowell needing to make up two.
The Irishman birdied the 17th, sending the final pairing to the final hole with both in search of the birdie they needed.
Furyk's chances evaporated when he plugged his approach shot in a bunker, But McDowell hit to 24 feet above the hole only to see his snaking, downhill putt to get into an 18-hole playoff slip agonisingly past.
Waiting nervously in the clubhouse, Simpson hugged his wife when McDowell's putt slid past and punched his fist in the air as the realisation hit him that he had won the US Open.
Earlier in the day, Tiger Woods saw his hopes of a 15th major title, four years after his last US Open win, rapidly crushed as he dropped six strokes in the first six holes.
The 36-year-old American eventually came in with a 73 and that, alongside his 75 on Saturday, was his worst weekend score relative to par in a major, casting fresh doubts over the current state of his game.