Rory McIlroy, of Northern Ireland, watches his tee shot on the seventh hole during a practice round at the PGA Championship golf tournament on the Ocean Course Wednesday, May 19, 2021, in Kiawah Island, S.C. (AP Photo/Matt York)

KIAWAH ISLAND, S.C. — The PGA Championship has become known for having the toughest field that faces the fairest test among the four majors in men's golf. But being fair doesn't mean it can't be a brute, the overriding topic of conversation so far this week about the Ocean Course at Kiawah Island.

It's not just the length, tipped out at 7,838 yards, because no course seems too long in today's game.

Throw in the stiff wind off the Atlantic Ocean — and the fact that two loops combine to offer nine holes in one direction and nine in the other, so it doesn't matter which direction it blows. Add putting surfaces that appear elevated because of the severe, shaved slopes.

"This golf course is a beast," reigning U.S. Open champion Bryson DeChambeau said Wednesday. "I'm sure the tee boxes will be moved up in certain areas, but for most players out there, if you don't hit it long, it's going to be a tough week."

The real measure? Big hitters getting reacquainted with a 3-iron or more on par 4s and par 3s.

Dustin Johnson hit his 7-wood on the par-3 14th hole and on the 505-yard closing hole. It was either that or his 3-iron, and the fairway metal lands a little softer.

"I think I've used every club in my bag so far," Johnson said Wednesday. "It just requires you to do everything well. Driving is definitely a big part of it. You've got to hit the fairways. They are fairly generous, but with the wind and the way the holes are angled, you've got to hit good drives to get it in the fairway.

"And then obviously from there," he added, "doesn't get a whole lot easier."

Rory McIlroy won at 13-under-par 275 when the PGA Championship was at this South Carolina island course nine years ago, though that's a little misleading on what the scores were really like. McIlroy is among the best in the world, and he was at his best during that tournament in August 2012 as he won his second of four major championships. Runner-up David Lynn finished eight strokes back.

Multiple tee boxes have been in play during the practice rounds, and the PGA Championship will decide which ones to use depending on the forecast for wind. It most likely will not play to its full length throughout the tourney. Players have been advised that some tees will be moved forward.

"Seriously, I hope so," Jon Rahm said.

During his practice round Monday, Rahm said the shortest iron he hit into a green from the 14th hole until the end was a 5-iron.

"I'm not usually the shortest hitter," Rahm said. "I was playing with Zach Johnson, and I think he pulled a head cover on every single hole except the par-5 16th coming into the green. For the sake of our sanity, I believe they're going to use a couple of forward tees."

Whatever the length, at Kiawah it's all about the win — which could switch directions at some point during the event, according to the forecast.

DeChambeau has tried to solve every equation for every variable in golf, except for wind. Not that he hasn't tried.

"Man, you guys are going to eat this one up," he said, bracing his audience for a spiel on science. "But the laminar flow of the wind and how it works I mean, look, there are certain times where over certain dune hills and stuff on greens and before the greens where the wind will flow down and up and over certain mounds, so that's going to make it feel weird, play different, and it's just going to affect how the ball goes."

Golf architects Pete and Alice Dye probably didn't consider laminar flow when they designed the Ocean Course. But it was built for wind, and that's been the best defense as long as golf has been played.

It starts to unfold Thursday with a field that features 99 of the top 100 players in the world, each of them offering different assessments on which part of his game needs to be the sharpest.

McIlroy is trying to end seven years without winning a major but is coming off his first victory of any type in 18 months, the Wells Fargo Championship two weeks ago. Jordan Spieth is again going after the final leg of the career Grand Slam, this time with four straight top-10 finishes, including his first win since 2017.

Collin Morikawa, who won the 2020 PGA Championship nine months ago, has as much recent experience as anyone. He came to Kiawah for a preview day a month ago and played in an opposite wind compared to what players have experienced this week.

Morikawa is known for his irons, not so much his length. He sees that as an advantage no matter how long and tough Kiawah plays.

"Out here with the wind, no matter what it is, you just have to control your golf ball," Morikawa said. "So it doesn't matter if you're 150 yards or you're 200 yards (out), you have to be able to know where you're going to land certain shots, where you're going to miss them."

Phil Mickelson was looking where to miss on the 207-yard fifth hole, tossing golf balls behind and to the left of the hourglass green. He hit some mini flop shots from a small swale before telling his brother: "It's pretty easy (going) long. It's back uphill and into the wind."

There is length. There is wind. There is major championship pressure.

It's shaping up to be an extreme test, with DeChambeau venturing the winner very well may be the golfer who is "most patient."

"It may not be the person that's playing the best," he added. "There's certainly luck involved this week with the greens the way they are and the wind the way it is and the slopes around the greens. Sometimes you're just going to get unlucky. It's going to be somebody that has a lot of patience and a lot of resolve to fight back when things aren't going well for them."