SAN FRANCISCO – Social distancing protocols were ignored Sunday at TPC Harding Park in the final round of the 102nd edition of the PGA Championship.

In the end, however, Collin Morikawa stood alone with the Wanamaker Trophy.

On a raw, gray day that broke with dense fog, the crowded leaderboards at TPC Harding Park were volatile and seriously lit with a superb and large cast of the game’s best players delivering heart-pounding drama that kept the viewing public and players alike on edge.

In all, nine players held at least a share of the lead at one time or another in the final round of the first major of the year. Deep into the back nine, 10 players were within two shots of the lead and seven players were sharing residence at the top of the leaderboards.

“There was a lot of kind of whiplash,” 2015 PGA Championship winner Jason Day said. “Everything was coming and going.”

And then the California Kid stole the show. In just his second major, Morikawa, a pup at 23 and the shortest hitter among the contenders, grabbed the outright lead by chipping in for birdie from 40 feet on the 14th and then teed up the defining shot of the tournament when he drove the 294-yard, par-4 16th and then knocked in the 7-footer for eagle and a 2-shot lead that he held to the end.

“I’m on Cloud Nine,” said Morikawa, a former University of California standout. “When I woke up today, I was like, this is meant to be. This is where I feel very comfortable. This is where I want to be, and I’m not scared from it.

“I think if I was scared from it, the last few holes would have been a little different, but you want to be in this position. It just gives me a little taste of what’s to come. I got a taste of this now. Obviously, it was a very crowded leaderboard. At one point if you looked at the leaderboard it was all at 10 under and it was a party pretty much. So this one is going to be very special.”

Morikawa closed with a bogey-free, 6-under-par 64 to finish at 13 under and two shots clear of Paul Casey —who at 43 was trying to become the oldest first-time major winner since Roberto de Vicenzo won the 1967 Open Championship at 44 — and 54-hole leader Dustin Johnson, who became the first player to go 0-for-4 in majors after holding the 54-hole lead. Casey shot 66, Johnson 68.

In a tie for fourth, three strokes behind were Matthew Wolff (65), Day (66), Bryson DeChambeau (66), Tony Finau (66) and Scottie Scheffler (68).

Brooks Koepka, trying to become the first to three-peat in the PGA Championship since it went to stroke play in 1958, began the day two shots out of the lead but shot a disappointing 74 to finish in a tie for 29th. The four-time major winner came into the tournament on a 1-T2-1-2-T4 roll in the majors.

“It’s my first bad round in a while in a major,” Koepka said. “Wasn’t meant to be. Three in a row, you’re not really supposed to do two in a row looking at history, but that’s all right. Got two more the rest of the season and we’ll figure it out.”

Fifteen-time major winner Tiger Woods, seeking his fifth Wanamaker Trophy, finished with his best round of the tournament, a 67, and tied for 37th.

As for Morikawa, he wasn’t making his first star turn as he’s already been linked to some of the game’s greatest players. He made the cut in his first 22 tournaments as a pro – bested in the last 30 years only by Woods’ 25. Morikawa now has as many majors as he has missed cuts.

Leaderboard | Photos | Winner’s bag | Money | Trophies

He began his pro career on an impressive note when he won the Barracuda Championship last year in just his sixth start. Last month, he bested Justin Thomas in a thrilling playoff to win the Workday Charity Open. Now he moves to No. 5 in the Official World Golf Rankings.

And he joined Woods, Jack Nicklaus and Rory McIlroy as players who won their first PGA Championship at age 23.

From the get-go, he’s always looked comfortable on all of golf’s stages and he felt right at home this week after playing his fair share of golf at TPC Harding Park as an All-American standout at Cal.

He’s already talked about as one of the best iron players in golf. Not bad around and on the greens, too. And he gets by without being one of the longest in the game. This week, he ranked 51st in the field in driving distance but was first in driving accuracy. He also led the field in proximity to the hole with his approach shots and in Strokes Gained: Putting.

But it was his drive on 16 that will not soon forget.

“By Wednesday night, I had no plans on going for 16 at all,” said Morikawa, who was tied with Casey at the time of his unforgettable tee shot. “It’s too much into the wind, why go for it. It was like 278 to the front, and just a good drive for me. It was going to land just short of that in this weather; it’s going to bounce on up. (My caddie) looked at me, he counted off and asked me what I wanted to do and I told him, let’s hit a good drive. And stepped up, and those are moments I’m always going to remember.”

Morikawa’s playing partner, Cameron Champ, has a long history dating to junior golf with Morikawa. Champ, who shot 70 to finish in a tie for 10th, wasn’t surprised at Morikawa’s march to his maiden major.

“He knows his game and what works for him,” Champ said. “His iron play and off the tee is amazing. He rarely misses a shot and obviously, his putting and chipping is all world-class, as well. He earned it, he deserves it. I give him props.”

So, too, did others.

“He’s clearly an unbelievable ball-striker, and something that I envy and hopefully I can get there one day,” DeChambeau said.

“He’s a heck of a player,” Finau said. “He doesn’t have a weakness in his game. He doesn’t have a weakness mentally. So when you’re dealing with that type of talent, he’s going to be somebody to beat in major championships for a lot of these things.

“This isn’t a guy that’s just going to pop up and disappear for the next five years.”

Morikawa is intent on making sure that doesn’t happen.

“It doesn’t stop here,” Morikawa said. “I’ve got a very good taste of what this is like, what a major championship is like. The majors are going to be circled in, just like everyone else, but I’ve got to focus on every single week.

“I’m trying to win every single week. I’m not trying to come out and just win the majors. I’m 23. I love golf. I love every part of it. I love being in this position and I love just being able to come out here and play with a bunch of guys that love the sport, too, and that’s why I think I love being in this position.”