MAMARONECK, N.Y. — What was supposed to be a typical U.S. Open produced a most unconventional champion.

Bryson DeChambeau was not the least bit concerned by the narrow fairways or the ankle-deep rough that shape Winged Foot into historically the toughest of all U.S. Opens. With his extra 40 pounds of muscle and mass, he wanted to pound it into submission with his driver, even if his errant shots were buried in deep grass.

That’s how he plays the game. And for skeptics who said that wouldn’t work in a U.S. Open at Winged Foot, just look at that shiny silver trophy he kissed, and the record score he posted Sunday in a six-shot victory.

This victory was as much about validating his out-of-the-box approach to the royal and ancient game.

“One hundred percent, no doubt,” DeChambeau said. “For me, it’s about the journey of can I executive every shot more repeatable than everybody else. I was able to do that this week. That’s why I won by six.”

Part of this course’s fame is the “Massacre of Winged Foot” in 1974 when the winning score was 7-over par.

This was a massacre, all right.

DeChambeau rolled in a 7-foot par putt and thrust those powerful arms in the air when he capped off a 3-under 67 on a course that didn’t allow another round under par. Two shots behind Matthew Wolff at the start of a chilly September afternoon, he caught him in four holes, passed him in five and pulled away along the back nine.

From the fairway. From the rough. It didn’t matter.

“I don’t really know what to say because that’s just the complete opposite of what you think a U.S. Open champion does” Rory McIlroy said. “Look, he’s found a way to do it. Whether that’s good or bad for the game, I don’t know, but it’s just not the way I saw this golf course being played or this tournament being played.”

Call him a mad scientist in a tam o’shanter cap. Call him a game-changer in golf.

Any description now starts with U.S. Open champion.

Wolff, trying to become the first player since Francis Ouimet in 1913 to win the U.S. Open in his debut, closed with a 75. He made a 10-foot eagle putt on the par-5 ninth to stay within one shot. That was his only hole under par. Wolff finished at even-par 280, a score that would have won four of the previous five U.S. Opens at Winged Foot.

It didn’t stand a chance in this one.

“You can’t take Bryson out because obviously he won, but shooting even par for four rounds at Winged Foot is pretty exceptional,” Wolff said.

That describes DeChambeau this week. It was a breathtaking performance, four rounds at par or better, the first player to manage that at Winged Foot.

His victory really began last October, when he closed out his 2019 season in Las Vegas and said with a mischievous grin, “I’m going to come back next year and look like a different person.” He added 40 pounds through intense workout and a diet of 6,000 calories a day.

The COVID-19 pandemic shut down golf for three months, leading to the U.S. Open being postponed from June to September. It also gave DeChambeau more time to execute his plan of swinging faster and harder, stretching the limits.

His work ethnic borders on insanity, and the eve of the final round was no exception. Unhappy with how he played Saturday, hitting only three fairways, DeChambeau had the lights turned on so he could stay on the range well past 8 p.m., pounding driver, searching for the right swing. Temperatures were in the 40s. He was in a short-sleeve shirt.

He didn’t find fairways, but he seemed to miss in the right spots. That was key for a player who hit only six fairways on Sunday, 23 out of 56 for the week.

Skepticism turned into admiration, with a healthy dose of disbelief.

“It’s a game we’ve never really seen before,” said Harris English, who shot 73 and finished fourth.

Louis Oosthuizen birdied the 18th to finish alone in third.

“I don’t think they can set it up for him, to be honest,” Oosthuizen said. “I don’t know what they can do really, because he’s hitting it so far. He’s so strong out of the rough. And he’s probably one of the best putters out there, which a week that he really putts well, you’re going to have a lot of trouble.”

In six U.S. Opens at Winged Foot among 894 competitors, DeChambeau is only the third to finish a tournament under par. His 6-under 274 was the lowest score, and no one saw it coming this week.

Wolff, the 21-year-old Californian who can drive it past DeChambeau with a lower flight and more roll in the fairway, gave him a good run in his quest to become the youngest U.S. Open champion since Bobby Jones in 1923.

The U.S. Open was still up for grabs for a fleeting moment around the turn. DeChambeau and Wolff each got out of position on the eighth hole and made bogey. DeChambeau was at 3 under, one shot ahead of Wolff. Ahead of them, Oosthuizen and Xander Schauffele were lurking at even par.

Still to play was the back nine, where so much has gone wrong at Winged Foot over the years.

Not this time.

DeChambeau and Wolff blasted drives down the fairway on the par-5 ninth. DeChambeau rolled in a 40-foot eagle putt with perfect pace. Wolff, who had pitching wedge for his second shot, matched his eagle with a 10-foot putt.

Just like that it was a two-man race.

And then it was a one-man show.

Wolff’s tee shot on the par-3 10th rolled left into the thick collar of the bunker, a spot so precarious he had to stand in the deep bunker and grip halfway down the steel shaft of his sand wedge. He chipped 10 feet by the hole for a bogey to fall two shots behind.

From the fairway on the 11th, however, Wolff hit wedge that was chunky and went into the right rough, and he had to scramble for par instead of setting up a reasonable birdie chance. DeChambeau from the right rough came up short, but he used putter from off the green for birdie from 15 feet away.

With a three-shot lead, DeChambeau kept blasting away as if he were chasing, not leading, just like he said he would. He saved par from the left rough on the 14th and a perfect pitch from deep grass behind the green. He downed another protein shake walking down the 15th, marching along to a major title that affirms his position in the game as a pioneer.

Imagine the USGA, which has been studying the impact on distance, getting together for a debriefing after this performance. What would they say?

“He’s hitting it forever,” DeChambeau said with a laugh.

The last laugh.