The U.S. Open won Webb Simpson on Sunday at the Olympic Club.

Someday, maybe even Monday morning, he’ll wake up and ask, “How did that happen?” Actually, he’s already asking it and he doesn’t have an answer. Not that he cares. He’s too busy grinning, reading the 135 texts on his phone and, in his disarming way, sharing the marvelous mysterious magic — sometimes it really is that corny — of these mischievous U.S. Opens that decide to produce a shocking winner.

For such things, Olympic is an absolute favorite venue. In ’66, Billy Casper never dreamed he’d beat Arnold Palmer when he trailed by seven shots with nine holes to play. Billy even asked Arnie to help him hold together to finish second. In ’55, Jack Fleck never thought he’d beat Ben Hogan in an 18-hole, head-to-head playoff. And Scott Simpson and Lee Janzen, though exceptional Open players, were out-of-the-blue winners here.

But Webb Simpson came in so low under the radar, after missing the cut in his previous two events, that the Air Force ought to try to patent his stealth technique. Yes, he was the No. 2 money-winner on the PGA Tour last year and came here ranked 14th in the world. But he’s been in a recent slump, fixing swing flaws, then, as recently as last week, fixing the flaw’s flaws.

“I never really wrapped my mind around winning at any point,” said Simpson who began the day tied for eighth place, shot a 2-under-par 68 to post a 1-over 281, then waited to see if the third-round co-leaders would complete their collapse and hand him the championship of his nation.

They did. Jim Furyk and Graeme McDowell, both former U.S. Open champions, needed to shoot a one-over-par 71 to win outright or 72 to force a Monday playoffs, but both finished bitterly disappointed, with a 74 and 73 respectively. “The tournament was mine to win,” said Furyk, who never made a birdie and bogeyed the sixth, 13th, 16th (to fall out of the lead) and the 18th when he was forced to gamble for birdie.

“I’ve been a leader-board watcher all my life, but I didn’t think it could help me today. That course is so tough you can make three or four bogeys in a row at any time. I just tried to keep the ball in front of me,” said Simpson, locked in the moment all day and gloriously oblivious. “After I finished 18 [saving par from the fringe] was the first time I looked at a scoreboard since early on the front nine.”

Simpson sat with his wife, looking at video of their baby boy to calm his nervousness as he waited to see if either Furyk or McDowell could birdie the 344-yard 18th hole and force a Monday playoff.

“I did not want to play again tomorrow,” Simpson said.

Lest Simpson’s shock and natural modesty be used against him, lets point out firmly that he’s a qualified, deserving winner though — okay — his $6.3-million ’11 season is his only letter of introduction to the world and his ’11 start had been a little slipshod.

How could a player who’s relatively young burst from eighth place to win and, while you’re at it, Webb, what’s up with this 15 winners in golf’s last 15 major championships?

“The Tiger effect has inspired players everywhere. There was a 14-year-old who made this field and a 17-year-old [Beau Hossler] was on the leader board this weekend,” Simpson said. “Maybe a player’s prime used to be their mid-30s, but I think now maybe it’s your mid-to-late 20s. When I saw Keegan Bradley [also 26)] win [the PGA Championship] last year, I thought if he can win [a major], then I can win one.”

The youth movement seems to be reaching almost absurd, though amazing extremes.

“Teenagers? In college, I’d have been scared to death to win,” said Simpson, who had an Arnold Palmer scholarship at Wake Forest. “I hope this makes Arnie smile,” he said, knowing ’66 still annoys Palmer.

As in every shock-winner story, there are the sad favorites who faded under pressure. Furyk, the well-rounded, smart guy you’d want to go to dinner with and take the wives, and the life-loving, funny McDowell, who’d be ideal company for a ballgame and beers, are an especially hard pair of tough-luck losers to accept.

“This course makes you play cut shots to hold the fairways and greens,” McDowell said. “So, you practice ‘cut, cut, cut’ long before you ever get here. By the time I needed to hit the ball straight [on Sunday] or draw it off the tee at the 17th, I just didn’t have those shots anymore.”

Like so many last-group leaders in previous years, Furyk and McDowell seemed to be locked in a distracting match-play-style duel, especially on the front nine. Add them to the list of those who’ll say, “I only needed 71 or 72.” On the final leader board by the 18th green, these were some of the scores staring down at them: 67, 68, 68, 68, 70, 70, 70 and 71. When you’re chasing at the Open, like Simpson, it’s far from an easy task, but it’s less preposterously difficult. Once again, the lead was an anchor.

Simpson was smacked squarely in the face with bogeys on the second and fifth holes. That’s when he said he vowed to stop scoreboard gazing. Soon, he was refocused on his work and went on a five-hole blitz that set the stage for his title, birdieing the sixth, seventh, eighth and 10th holes.

His last act was his most dramatic. At the 18th hole, he faced an up-and-down for par from a bare-patch lie beside the green. His chip from 35 feet nestled within a yard of the cup and “with hands shaking,” Simpson knocked it in the heart, finally locking him in the lead at 1-over 281.

Yes, the U.S. Golf Association had its revenge. After Rory McIlroy shattered the Open record with a 16-under-par performance last year at Congressional Country Club in Bethesda, not a mortal soul could break their sacred par this year. And many of the game’s biggest names lay decimated.

As an early afternoon fog dissipated, then swept back over the course at dusk — you never know what you’ll get next here — Simpson celebrated by letting out a scream of joy. His grin couldn’t have been larger, though it was probably locked in a five-way tie with those other shocked and delighted Olympic winners: Fleck, Casper, Scott Simpson and Janzen.

When the Open comes here, nobody knows who’ll win or why. Not even the winner. Not even after he’s won.

For previous Thomas Boswell columns, visit washingtonpost.