This time, DeChambeau was stone-faced. The heckler, a man named Lee Woody holding two cans of White Claw hard seltzer, seemed pleased when DeChambeau missed the green on the par 3.

“There’s a line, and I dip my toes in there a little bit,” Woody said of his taunting. He had wagered another $100 through FanDuel on Hideki Matsuyama to shoot under 71.5 that day. “He’s very calm and composed,” Woody said of Matsuyama. “He doesn’t get rattled by anyone who chirps.”

Neither, apparently, does DeChambeau, who saved par and went on to shoot a 67 en route to his second U.S. Open victory.

This was the first U.S. Open played in a state with legal sports betting, allowing spectators to wager from their phones on every imaginable aspect of the tournament, and jeers from gamblers in the gallery added one more challenge at the brutally difficult Pinehurst No. 2. One fan called out to Viktor Hovland on Friday that his bet depended on Hovland making the cut. (He did not.) Another offered to bet Phil Mickelson, an admitted gambling addict, on how he would do on No. 17.

“We hear everything,” DeChambeau said early in the week. “It’s not like we’re oblivious to it.” He joked that it’s harder to make out what hecklers say at LIV Golf events, which play music during rounds, adding: “Whether betting is a good thing or not is up for debate. I personally think if it can help grow the game and bring in a bigger audience, I’m all about it.”

Golf gambling and daily fantasy contests have exploded in recent years. PrizePicks, a daily fantasy operator, said it collected more than twice as much money in entry fees on the first round of this year’s U.S. Open compared with 2022. Betting during rounds, as opposed to before play starts, accounts for 45 percent of the money wagered on golf at DraftKings, the sportsbook said, and for some, attending a golf tournament offers a chance to capitalize on variables invisible to the TV audience, to bet quickly before sportsbooks can adjust their odds or, in some cases, to try to get inside players’ heads.

Two-time major winner Collin Morikawa said he hears fans calling out about gambling all the time, though usually to cheer him on. “In many other sports you would never hear that because you’re not that close and it’s too loud,” he said. “It’s just funny to think that we would play harder just for them.”

Fans could wager last week not only who would win but also the winner’s nationality, on finishers in the top five (and top 10 and top 20), the leader after each round, the best performance in each group (for the day and on each hole), a group’s aggregate score on a hole, how many birdies and bogeys each player would get per day and even whether certain players would hit a particular fairway or stick their approach shot within 20 feet.

Max Homa agreed that most of what gamblers yell during tournaments seems well intentioned. But he also mentioned last year’s BMW Championship in Illinois, where a gambler shouted “pull it!” while Homa was mid-putt. Worse than any on-course taunting, he said, is what gamblers send him via social media, which “gets really, really ugly.”

Bettors also have tracked down his Venmo account and multiple times per week send him requests for cash after his play costs them money. “That gets old,” he said.

Serious bettors craft predictive models to gauge how each player’s tendencies — driving distance, a preference for hitting draws or cuts, chipping and putting, performance in different weather — fit that week’s course. Beating bookmakers, however, has gotten much harder in recent years as granular golf data becomes widely available. When Rufus Peabody, described by one sharp bettor as the “apex predator” of golf gamblers, began wagering on the sport 15 years ago, he said he could gain an edge simply by recognizing that long-driving players have a leg up on longer courses.

Although Peabody’s approach is largely data-driven, golf allows for some subjective analysis, he said. At this year’s Pebble Beach Pro-Am, Peabody figured heavy rain would be especially bad news for Scheffler, who unconventionally slides his back foot on drives.

Gamblers covet nonpublic information, and there’s more of that in golf than perhaps any other sport. Before this year’s Masters, Golf Digest gambling analyst Andy Lack remembers spotting Hovland working with his swing coach on an empty driving range at 6 p.m. “Going to golf tournaments for years, you’re able to see who’s comfortable and who’s really grinding,” Lack said. (Hovland went on to miss the cut.)

Another time at the Masters, Alex Blickle, an analyst at FTNFantasy, noticed Paul Casey struggling to loosen his back during a practice round. He withdrew hours before the first round. Kenny Kim, host of the Fantasy Golf Degenerates podcast, placed a winning bet on Sergio García, a traditionally iffy putter, to win the 2017 Masters after seeing him draining putt after putt on the practice green.

Last week, one sharp bettor, who requested anonymity because sportsbooks are known to limit how much customers can bet after they show winning tendencies, scouted Pinehurst No. 2 during all three practice rounds, hoping to see whether it was as difficult as advertised. Players didn’t seem doomed when a drive found the wiregrass — giving a boost to long drivers, such as DeChambeau and Rory McIlroy, who might not be as accurate — and No. 16 didn’t seem quite as birdie-proof as suspected. SuperBook Sports set the line for the winning score at 5 under par, and this bettor felt confident wagering it would be lower. (DeChambeau finished 6 under.)

Players, caddies, credentialed press and volunteers are prohibited from betting on the tournament or passing nonpublic information to gamblers. But golf tournaments would seem to be a prime venue for “courtsiding,” in which in-person bettors wager on outcomes that have already happened before word has reached bookmakers. This was a problem roughly a decade ago, when sportsbooks relied on TV broadcasts that might be a minute or more delayed, said Matthew Trenhaile, a longtime British bookmaker. “If you were really lucky, you could get the feeds that literally come out of the broadcast truck if they were leaked or hacked.”

Betting groups would also send “runners” to golf courses to relay news such as whether a contender hit into a hazard or had a bad lie. But if bettors are able to beat bookmakers to the punch, it doesn’t take long for that to become apparent. “Bookmakers are very vindictive,” Trenhaile said, and bettors suspected of courtsiding often aren’t able to bet more than a few dollars.

Nowadays, sportsbooks can use geolocating to tell whether a mobile app user is on the course. “The guys who really industrialize the process open up with 50 odd accounts,” Trenhaile said, “and by the end of the tournament all those accounts are burned.”

Even if spectators see a bad lie before anyone else, most fans aren’t able to intuit how the odds should change. On No. 7 at Pinehurst, a par 4, a group of avid bettors perched among the pines saw American Charlie Reiter’s tee shot roll up against a tree. “It’s unplayable!” they exclaimed. Reiter hit his next shot to the middle of the green and made par.

Sam Cooney, the top golf oddsmaker at Circa Sports, said in addition to limiting “anyone with a pulse” who’s live betting on golf, many operators will build in a 10 percent or higher house edge in the odds “on something that should have a 4 or 5 percent edge” — a change most recreational customers don’t even notice, he said.

Fans streaming NBC’s coverage of the U.S. Open were likely seeing a delay of 30 to 50 seconds, according to analysis by technology company Phenix, but spectators at the event still couldn’t capitalize on that. For one, most sportsbooks use a data feed provided by IMG Arena delivered a second or two after a ball comes to rest.

Friends Miles Wilkins and Christophe Cabanne found seats behind one hole and hoped to spend their Thursday afternoon live betting on each group that passed by, only to find that FanDuel wouldn’t let them bet on anyone actually playing the hole. “Live betting is something you do impulsively, like buying a Snickers at the checkout counter,” Wilkins said after he and Cabanne left to find something else to do. “You’re not going to go back to an aisle to get it.”

Gambling from the gallery

A few recent high school graduates from the Charlotte area seemed to be having a blast Friday, sitting behind the 15th green, a par-3, and betting on every passing group. One of them, Hunter Justice, 19, also came Thursday but didn’t do any gambling. “I was here with my mom,” he explained.

Sports bettors in North Carolina must be 21 or older. One of Justice’s friends said he placed bets before the round on his brother-in-law’s FanDuel account but otherwise uses PrizePicks, which is 19 and up.

From their seats, the friends looked at FanDuel to find odds on each group playing 15, then placed $5 bets among themselves. Justice challenged his friend that García would make par or better. The Spaniard’s tee shot found the front of the green but, like so many shots that day, rolled off.

Nevertheless, García putted to four feet and made par. “Bang!” Justice said. As García left the green, he called out, “I love you and your stupid pants.”

It was easy to overhear fans boasting and fretting about their bets at Pinehurst. Tyler Cadd followed Tiger Woods during the practice rounds and, on the bus to the course Thursday morning, saw that the pin on Woods’s first hole was in the center and bet that he would make a birdie, which he did, at odds of +220, meaning a $10 bet profited $22. Another fan, Eric Allen, bet on Woods and several other players to win the tournament. “If somebody’s going to take a bet, I’ll bet on raindrops,” he said. “I don’t care.”

Since states began legalizing sports betting, there are only few reported instances of what Homa experienced: a gambler trying to sway the outcome of a shot. Still, “the potential for fan interference concerns me,” said Matt Kuchar, a nine-time winner on the PGA Tour. “You hope that it doesn’t come to the point where you need to do something that lessens the fans’ enjoyment of the game.”

Asked whether he’s concerned about widespread gambling diminishing the spectator experience, Jon Podany, chief commercial officer of the U.S. Golf Association, said simply, “We have not experienced this.”

Whether betting diminished Alex Gaspard’s experience at Pinehurst seemed debatable Thursday after the golfer he wagered $25 on to win, Justin Thomas, bogeyed nine holes in his first round.

Gaspard, who came from Texas to watch the U.S. Open, seemed miffed that his bet was doomed so quickly. Then again, he noted, “I’ve spent $25 on hot dogs already.”