Long-hitting American Dustin Johnson, seeking major redemption after several near-misses in recent years, won the U.S. Open on Sunday amid initial uncertainty over his victory margin.

Seeking his first grand slam crown, Johnson played clutch golf under intense pressure on a brutally difficult layout at Oakmont Country Club in western Pennsylvania.

Having negotiated the final seven holes under notice that he might be penalized for a rules infraction on the fifth green, despite being cleared by another official at the time, he was docked a shot after the round's completion, with his score amended to a closing 69 for a four-under winning total of 276.

Dustin Johnson Dustin Johnson holds the championship trophy after winning the U.S. Open golf tournament at Oakmont Country Club. Photo: Michael Madrid-USA Today Sports

He finished three shots in front of fellow Americans Jim Furyk and Scott Piercy and Irishman Shane Lowry.

Johnson's ball appeared to move slightly as the world number six was preparing to attempt his par putt at the fifth hole. He denied having caused the ball to move and the official accompanying the pairing decided not to levy a penalty.