SOUTHPORT, England — Now that the PGA Championship in Charlotte next month has gone from a big deal to a big-big deal because of Jordan Spieth, there is no telling where he might lead us. On Sunday, of course, he led us way up a dune.

It has gone past curious and wound its way to amusing, the human contradiction Spieth presents in a world full of contradictory humans. At once, he is a 23-year-old person who shows little attention-neediness and zero capacity to preen, and a 23-year-old golfer who already has assembled some of the most shocking, attention-hogging Sunday golf of the young century. He tells of his rounds in an unexcitable, calming voice that could lead us all into meditation, while the subjects of which he speaks sound absolutely berserk, because they were.

He doesn’t mean to do all this, of course.

“Seventeen pars and birdie would have been fine, too,” he said Sunday after he won the 146th British Open with eight pars, five bogeys, four birdies, one eagle, one climb up a dune way wayward on No. 13 to search for his ball, one blind shot over the dune on No. 13, one apparent collapse and one mighty stemming of one apparent collapse.

Maybe for Charlotte, he’ll feel free to play boringly. “I think there’s no pressure,” said his treasured caddie, Michael Greller. “He’s absolutely free-rolling it. He’s going to play in 30 more PGAs the rest of his life.”

Of course, if Spieth wins one of those 30, he will become only the sixth male player to complete the career Grand Slam as constituted since 1934. If he wins this particular one Aug. 10-13 at Quail Hollow, he will become the youngest at 24 years, 17 days. Tiger Woods was 24 years, five-plus months when he won – no, destroyed – the 2000 U.S. Open at Pebble Beach to complete his set. Jack Nicklaus was 26 when he took the 1966 British Open. Gary Player was 29 when he won the 1965 U.S. Open and thus all four. Gene Sarazen was 33 when he won the 1935 Masters, which was only the second Masters. Ben Hogan was 40 when he won the British Open in 1953, although any mention of that needs this blaring accompaniment: on his first and only try.

Like Rory McIlroy, who lacks only the Masters, Spieth edges toward a microscopic circle. “I’ve answered this question a few times a couple years ago (when he won the 2015 Masters and U.S. Open at 21), so I’ll be careful with my answer,” Spieth said. “It’s amazing. I feel blessed to be able to play the game I love, but I don’t think that comparisons are – I don’t compare myself. And I don’t think that they’re appropriate or necessary. So to be in that company, no doubt, is absolutely incredible. And I certainly appreciate it. . . .

“But I’m very careful as to what that means going forward, because what those guys have done has transcended the sport. And in no way, shape or form do I think I’m anywhere near that, whatsoever. So it’s a good start, but there’s a long way to go.”

Of course, he formed this measured, thoughtful answer after playing an off-the-wall round that also included bizarre minutes spent roaming near the driving range on No. 13, trying to find the suitable drop spot. He formed it after a 2016 Masters that remains inexplicable 15 months later, when he held a five-shot lead with nine holes to play, seemed the least likely guy to lose six strokes across the next three holes and then went bogey, bogey, quadruple bogey, then actually righted himself back to contention before finishing runner-up. He formed it after a 2015 U.S. Open in which he arrived at No. 17 with the lead, then went into some Seattle-area flora, then three-putted for double bogey, to see all of it deluged in memory by Dustin Johnson’s misadventure on No. 18 that took Johnson from a win to a playoff to a loss, all in three putts. He’s so careful, and so wild.

Still, by Sunday morning, he seemed the least likely guy to squander a three-shot lead. As his ad at a mall near the pier in Southport read, “I WILL.” Then he up and squandered it within four holes and led everyone on a rowdy adventure.

All along, he carried along the ghouls from two Masters ago, in a way he wouldn’t admit Saturday evening. By Sunday evening, he said, “You know, I thought winning a few weeks later (in 2016) in Fort Worth was huge. But I knew that another major would be the one thing that would, I think, just completely, over the hill, you know, I’m capable of closing these majors out. Because you just – I really didn’t do much wrong (at that Masters), just hit a couple of bad swings.”