BETHPAGE, N.Y. — Jordan Spieth actually played pretty well Saturday for a guy who is still looking for his game and kept getting hit by shrapnel. Spieth was paired with the weapon of mass destruction that is Brooks Koepka in the third round of the PGA Championship, and so he had a pretty good sense of two things: How good Koepka is, and how far he has to go.

Koepka is the best player in the world in the tournaments that matter most, which makes him, to most pairs of clear eyes, the best player in the world. He is doing what Spieth did for a spell, what Rory McIlroy did for a spell before that, and what neither of those men has done lately: He is playing every shot at major championships like he knows he is better than the other golfers. And they know it. And he knows they know it.

Spieth absolutely must know it. And he kept finding out Saturday. He left his tee shot on the par-3 third hole in a greenside bunker. He left what should have been a straightforward approach on No. 6 short, in a bunker. He hit his tee shot on the par-4 ninth in a great spot on the fairway and still made double-bogey. At times his distance control was awful, and at others the player who used to say “aim small, miss small,” appeared to aim over there and pray a lot.

On the 15th tee, Spieth teed off first, found the right rough, and slammed his driver into the ground twice. As soon as Koepka struck his drive, Spieth started walking. He appeared steamed. He did not talk to the media after shooting his two-over 72—his agent, Jay Danzi, said nobody officially asked—but he did sign a bunch of autographs for fans lined up near the putting green. Spieth, on good days and bad, is eminently likeable.

His game just isn’t there yet. The galleries at Bethpage Black had to hope Spieth would fire a 64 and chase down Koepka, if only for the theater. If somebody was going to make this interesting, wasn’t Spieth the guy to do it? Isn’t he the 20-something you can never count out, who only needs a PGA to complete the career grand slam?

He is. But he isn’t right now. And what had to frustrate him is that Koepka did leave a little opening for anybody to burst through, and Spieth should have had the best chance, and he couldn’t do it.

Spieth began the day at five-under. Koepka was at 12-under. Koepka shot an even-par 70. It was an impressive even-par 70, because he was playing with the lead and made a preposterous birdie from the rough on the 13th and a more preposterous par from the rough on the seventh hole. But it was still an even-par 70.

Koepka stood still. Spieth went backward. If he had shot a 65, he would be at 10-under now, and Sunday would feel like a title fight. Instead, Spieth knocked himself out.

Spieth, whose struggles in the last two years are well-documented, is not ready to win major championships again. But the fact that he is tied for eighth the way he is playing is astounding—a testament to his mental game, his talent, and a hint that he is getting there.

“I’m 100% not hitting it as well as I did a couple years ago,” he said Friday, “but I'm hitting it a lot better than I did the end of last year, beginning of this year.”

He pointed to a tee shot Friday on No. 7—“a shot that I had no chance hitting this entire year. I just absolutely pummeled one, just a tight draw on my line when there was trouble right.”

Spieth is honest enough to admit he doesn’t have his game together but smart enough to realize that if he is in contention anyway, he has to believe he can win. He straddled that line Friday night, and then the predictable happened Saturday. He could not put together four straight rounds under major-championship pressure this week.

It will happen again, perhaps as soon as next month at the U.S. Open at Pebble Beach. But this was Brooks Koepka’s day, it is surely Koepka’s week, and at the moment it is Koepka’s sport. Whenever the old Jordan Spieth is ready, Koepka will be waiting.