KIAWAH ISLAND, SOUTH CAROLINA (AFP) - Blustery winds, marshland waste areas and even alligators welcomed the world's best golfers to formidable Kiawah Island on Monday (May 17) for the first official practice round of the 103rd PGA Championship.

The resort's Ocean Course will be the longest venue in Major golf history at 7,876 yards, 135 more than the mark set by Erin Hills when it hosted the 2017 US Open.

It is a par-72 layout Golf Digest has called the most difficult US course, with oceanside beauty and peril lurking on every hole.

"There aren't a lot of bailout areas," said 2003 PGA Championship winner Shaun Micheel. "There are a lot of things out there that are lying in wait for you."

Alligators are typically kept at a distance by security and course workers but there is nothing to stop the biting winds that swop direction.

"When the wind gets going out here, there's nothing to stop it," said Rickie Fowler, who received a special exemption into the field of 156.

"It can blow pretty good. There are no trees to stop it. When the wind gets up, it can blow pretty hard out here. A lot of it is determined by weather and wind."

The forecast is sunny throughout the tournament but with winds shifting from out of the East to out of the West between the first two rounds and the weekend.

Three-time Major winner Jordan Spieth, who snapped a four-year win drought last month in Texas, can complete a career Grand Slam with a victory along the South Carolina coastline.

"I feel like iron shots in the wind and controlling distances is a strength of mine, and hopefully that's what it comes down to," he said.

Spieth could become the first player to complete a career Grand Slam at a PGA Championship.

Seventh-ranked Rory McIlroy, coming off a victory two weeks ago at Quail Hollow, won the 2012 PGA Championship at Kiawah by eight strokes and seeks his first Major title since taking the fourth of his career at the 2014 edition.

The 32-year-old Northern Ireland star was out in shorts on Monday, joining other contenders in testing the greens and chipping areas around the holes.

Consistency, patience and shot-making precision will be tested with draws and fades needed for ever-changing challenges. Organisers will swop tee distances as well as pin placements to alter every hole, with sandy waste areas waiting to punish errant shots severely.

Thomas could take No. 1

The longest-ever Major course could play into the hands of long hitters like top-ranked Dustin Johnson, a home-state hero who won last year's Masters, and fifth-ranked Bryson DeChambeau, who overpowered Winged Foot last year to win the US Open by blasting drives for maximum distance regardless of landing area.

DeChambeau's lofty power hitting, however, could leave high shots open to the wayward winds off the water and sand or tall grass to swallow up off-target balls.

Second-ranked Justin Thomas could overtake compatriot Johnson for the world No. 1 spot this week with a victory if Johnson, who withdrew from last week's PGA Tour event with knee issues, finishes worse than sole fifth place.

Johnson has been a runner-up in the past two PGA Championships and was third in 2018.

Defending champion Collin Morikawa will try to become only the third player to win back-to-back PGA Championships since it became a stroke-play event in 1958, after Tiger Woods and Brooks Koepka.

The PGA Championship, as it has since 1994, boasts the toughest field in golf with 99 of the world's top 100 players in the field.

Woods, a 15-time Major winner, has been idled by leg injuries suffered in a February car accident. He fell to 103rd in this week's world rankings.

Everyone seeks the US$1.98 million (S$2.64 million) top prize from an US$11 million total purse. There are 35 Major winners in the field, 16 of them past PGA Championship winners, with a combined 56 Major triumphs.

A limited crowd of about 10,000 spectators daily will be allowed onto the course.