KAPALUA, Maui >> The 33 golfers who teed it up for Thursday’s first round of the Sentry Tournament of Champions had better get out the rule book.

There are several notable changes that went into effect at the first of the year that may have the golfers visiting rules officials more often the first few months of the season just to make sure they’re doing the right thing. There are too many changes to list, but the main ones deal with taking ball drops, pulling the pin, grounding your club in a hazard and fixing ball and spike marks.

The one garnering a lot of attention this week on Maui is leaving the pin in while putting. Bryson DeChambeau left it in on a variety of putts during the opening round, including a birdie effort of about 8 feet on the par-5 fifth that dropped him to even for his round. Playing partner and defending champion Dustin Johnson did not follow suit. He pulled the pin as most of the pros said they would do.

“I mean, personally, I don’t think I can,” a bemused Justin Thomas said on New Year’s Day. “I mean, if I have an 8-footer to win a golf tournament, I can’t. I mean, no offense, I can’t really take myself seriously if I kept the pin in. I mean, it just would be such a weird picture and like on TV me celebrating and like the pin is in and my ball’s like up against it. If I have a putt I’m trying to make that thing’s coming out.”

Johnson, who was paired with DeChambeau in the opening round, said there was a big poster in the locker room detailing the new rules. He believes the new ball-drop rule — which states you have to do it from knee level rather than your shoulder and that it must land inside of two club lengths — may garner the most penalty strokes until everyone gets used to it.

Johnson conceded it would be different leaving the pin in while putting. He said at first he would always pull it, then added later he might leave it in for a long putt, instead of having his caddie stand up there and pull it once the golf ball got close.

“It’s going to be weird because the flag’s going to be going in and out a lot,” Johnson said of Thursday’s round with DeChambeau. “But it’s all right. I mean, it’s not bad.”

Some of the other rule changes allow the golfer to fix ball marks and spike marks on the green, even those in the line of your putt. You can now ground your club in a hazard, but you can’t take practice swings in a bunker. You can remove loose impediments in the bunker like leaves and small rocks. You can also take a two-stroke penalty if you don’t want to try to hit the ball out of the bunker.

Most of the golfers asked about the new rules said their caddies would have to be knowledgeable about the changes. And that includes one where the caddie can’t stand behind the golfer to make sure he is lined up properly before putting or striking the golf ball.

Masters champion Patrick Reed, like Johnson, thinks the new ball-drop rule could be the one that causes players the most grief. The one he likes the most is fixing ball and spike marks on the green and removing loose impediments in the bunker.

“I think it’s huge being able to fix spike marks with how fast and slopey greens are these days,” Reed said. “I mean hitting a putt over a spike mark from 6 feet can make a huge difference than hitting over a flat spot.”

These rule changes are designed to make play go faster. At first, that might not be the case until the players grow accustomed to them. In the first few months, they may be calling on rules officials more than usual to avoid penalties or being disqualified.

Sony Open champ Kizzire gets hole-in-one

Reigning Sony Open in Hawaii champion Patton Kizzire had the shot of the day in Thursday’s opening round.

Standing on the tee at the difficult par-3 eighth that requires quite a carry over a gulch, Kizzire hit a 7-iron from 187 yards to about 5 feet from the pin that was tucked on the right side of the green and then watched as the ball rolled delicately into the hole like it was just a typical par putt.

It was anything but as Kizzire celebrated with his caddie after the rare ace at what is often the most difficult hole on the 7,500-yard course. The first golfer to do it in this event was Lucas Glover during the third round of the 2006 event. It propelled Kizzire into contention as he finished just three strokes behind opening-round leader Kevin Tway.

“Leish (Marc Leishman) hit a 6-iron and kind of hit it a little straighter and it was behind the hole,” Kizzire said. “And I said I’m going to hit 7 and work it with the wind. I told it to go, but it was perfect and it just hopped and just boom.”

Na withdraws with finger injury

Kevin Na withdrew from the tournament, citing an injury to one of his fingers. No other details were given. First-round playing partner Gary Woodland toured the 18-hole course by himself and shot a 6-under 67. Woodland trails first-round leader Tway by one shot.