American outsider Webb Simpson has won the 2012 US Open in San Francisco after carding a final-round 68.
The 26-year-old from North Carolina was not among those considered to be in contention at the start of play on Sunday.
However, four birdies in five holes around the turn dragged him up the leaderboard before he nailed a sublime up-and-down for par on the 18th to pile the pressure on his rivals.
Overnight joint-leader Graeme McDowell needed to birdie the last to force a playoff, but the 2010 champion failed to hole the 24-foot put that he required.
Simpson finished the tournament on one over, while McDowell and Michael Thompson were one shot behind in joint-second.
Jim Furyk, David Toms, Padraig Harrington, Jason Dufner and John Peterson all finished joint fourth on three over.
Ernie Els (+4) was ninth, while Lee Westwood (+5) ended up 10th.
