KIAWAH ISLAND, S.C. — It has been nearly two decades since Justin Thomas played the Ocean Course at Kiawah Island on the South Carolina coast, so he does not remember too much about the challenges other than watching his father, Mike, five-putt No. 3.

Justin needed a bit of a refresher. And after being sent a scorecard from the seaside course, he could not hold in his laughter.

“I saw that the back nine was 4,000 yards and I think I actually laughed out loud,” Thomas said, shorting the finishing nine holes – that includes the 608-yard No. 16 – by 61 yards.

Length, though, isn’t the most challenging aspect of the 103rd PGA Championship, which will boast the longest course in major championship history, 135 yards more than the 2017 U.S. Open at Erin Hills. As those who live near water know, where there’s ocean, there’s wind.

And with expected 10-15 mph steady winds with high gusts out of the northeast for three of the four rounds, including a possible shift to the southwest Sunday, at a course that is nearly 4.5 miles (7,876 yards) long and surrounded by grassy dunes and sandy waste areas, this will be nothing like last week’s Byron Nelson where K.H. Lee won at 25-under.

“I think this golf course is probably the toughest championship course on a day-to-day basis that these players will ever see, especially if the wind blows a little bit,” said analyst and two-time major champion, Curtis Strange.

When Pete and Alice Dye designed the Ocean Course, Alice wanted it raised for unobstructed views of the coastline from every hole. With that comes stronger winds. The PGA of America will try to anticipate the wind direction and adjust tees forward or back accordingly.

Something Jon Rahm said he was very happy to hear “for the sake of our sanity.”

Holes 1-4 and 14-18 play into the east-northeast wind. Those final five holes hug the coastline. The shortest iron Rahm hit into a green from No. 14 during one practice round was a 5-iron.

“I’m not usually the shortest hitter,” said the 6-foot-2 Spaniard.

“When you’re right on the ocean and you have a humid place, you have a lot more dense air. So what a 10 miles an hour wind might be here is definitely going to be different than 10 miles an hour some places inland. You’ve got to account for that. You’ve got to club it. You’ve got to adjust to it.”

Tony Finau played all 18 holes Monday from the tips to get an idea of how difficult it will be when the tees are their maximum length. The wind was stiff but not as bad as it will be Thursday and Friday (Saturday is forecast to be the most calm day). Finau hit his 3-iron, which he flights about 255 yards, on the par-3 No. 14. The hole is 238 yards.

“They can’t possibly play it that long,” said Thomas, who is grouped with Jupiter, Florida, neighbors Rory McIlroy and Brooks Koepka the first two days. They tee off Thursday at 8:33 a.m. ET from the 10th tee.

“They can’t play 14 back if you have this wind. Guys are going to be literally hitting driver on that hole. Unless the PGA wants seven-hour rounds, I wouldn’t advise it.”

All of which means No. 16 can play close to 750 yards. That’s according to Adam Scott.

“It’s probably numbers that we’ll never hopefully see on golf courses, but that’s what it’s playing like,” Scott said.

Then there is the other half. Holes 5-13 face the opposite direction, hence the need to adjust tees. Thomas says some of those holes can play up to 100 yards shorter with a strong wind to your back. On Tuesday, he hit an 8-iron into the green on his second shot on the 579-yard seventh hole.

McIlroy, as much as anyone, knows what his fellow golfers faced during those practice rounds. Nine years ago, a 23-year-old McIlroy won the PGA Championship at the Ocean Course for the second of his four majors. He closed with a 66 on a calm day to finish with a 13-under 275 and win by eight shots. That included a second-round 75, “which I was delighted with,” he said.

The stroke average for that day was 78.

Consistency and patience – and trusting your eyes – will determine the 2021 PGA Championship, that boasts a field of 99 of the top 100 in the world ranking, the exception being Matthew Wolff, who withdrew last week.

“I don’t really think about it,” McIlroy said about the conditions. “I get the wind, I get the number, I try to visualize what I’m going to do and then I try to replicate what I have just visualized.

“It sort of goes back to playing golf as you did as a kid, without a yardage book, and just sort of eyeballing it and playing it a bit more by feel.”