(Reuters) - A new year kicks off on the PGA Tour in Hawaii on Thursday at a tournament where the rules might get as much attention as the leaderboard.
A raft of changes came into effect on Jan. 1 in the biggest rewrite of the regulations in decades and will get their first professional test at the Kapalua Plantation course on the island of Maui.
Perhaps the most noticeable change is that players can now leave the pin in while putting, something that previously was not allowed.
Bryson DeChambeau, who majored in physics at university, turned some heads last year when he said his analysis had determined it was generally advantageous to leave the pin in.
The world number five has not changed his mind in the ensuing few months, though he said there would be one exception.
"It gets tricky when the flag's waving back and forth and I've got a five-footer and shadows," he told Golf Channel as he prepared for the tournament.
"That's the only time I would pull the flag out. Any time I've got a putt over 10 feet I'll probably be leaving it in, especially if it's uphill."
Fellow American Justin Thomas, however, said he would not be putting with the flagstick in.
"If I've got an eight-footer to win, I can't take myself seriously if I have the pin in," the 2017 PGA Championship winner told reporters.
While the option of removing the pin is easy to understand, other rule changes are more complicated, and Thomas said he expected players would err on the side of caution at first.
"I think you'll see it across the field especially these first couple (of) months, everybody's going to be calling a rules official in as much possible," he said.
"But I've tried to study up ... you would hate to get penalised just for making a mistake for something you've done your whole life, so it will be different."
The 34-man field in Hawaii is restricted to 2018 winners on the PGA Tour. Three players -- Tiger Woods, Phil Mickelson and Justin Rose -- qualified but are not playing.
Dustin Johnson is defending champion after winning by eight shots, while Rory McIlroy is making his first appearance.
The Northern Irishman previously has started his season with European Tour events in the Middle East, but has turned his focus to the PGA Tour.
"Taking up residence in the U.S. last year, being a permanent resident, I made the decision that this is where my life is going to be, this is where I'm going to live," he told reporters on Wednesday.
"I wanted to get (the year) off to a good start, an early start."
(Reporting by Andrew Both in Cary, North Carolina; Editing by Greg Stutchbury)