Bryson DeChambeau kept his nerve in a dramatic final round, back nine battle with Rory McIlroy to win the U.S. Open by one shot on Sunday.

Looking to end a decade-long major drought, Rory McIlroy fumbled at the end of his round with bogeys on three of his final four holes, including a heart-breaking drop shot at the 18th where he missed from inside four feet.

Playing in the final pair with McIlroy, DeChambeau hit his tee shot into the rough but held his nerve with a brilliant up and down to save par for a final round one-over 71.

That was good enough to earn the LIV Golf player a victory with a six-under 274 winning total and lift the U.S Open trophy for a second time since 2020.

"Oh, man, I didn't want to finish second again," said DeChambeau, runner-up at last month's PGA Championship.

"PGA really stung. As much as it is heartbreaking for some people, it was heartbreak for me at the PGA. I really wanted this one. When I turned the corner and saw I was a couple back, I said, nope, I'm not going to let that happen," he added.

Meanwhile, McIlroy returned with a final round of 69 to finish alone in second place, one shot ahead of Americans Patrick Cantlay (70) and Tony Finau (67).

DeChambeau started the day at the top of the leaderboard three clear of the chasing pack that included McIlroy but trailed the world number three by two with five holes to play.

"Ultimately on 13, I knew I had to make birdie there to give myself a chance because Rory was going on a heater," said DeChambeau, who collected his last birdie of the day at 13.

"He (McIlroy) slipped up a couple on the way coming in, and I just kept staying the course."

DeChambeau had looked headed for another second place until McIlroy's sudden collapse.

McIlroy had a hot streak with his putter to take the lead, but when he had to seal the deal, his putter had gone cold. The Irishman missed a 30-inch putt on the 16th hole and another one inside four feet on the 18th to lose chances of ending his decade-long major drought.

With the silver trophy, a record 4.3 million USD winner's purse golf bragging rights were also on the line with a LIV golfer again claiming a major title.

"I hope this can bridge the gap between a divided game," said DeChambeau. "All I want to do is entertain and do my best for the game of golf, execute and provide some awesome entertainment for the fans.

"From at least what I can tell, that's what the fans want, and they deserve that. Let bygones be bygones and go figure it out."