FARMINGDALE, N.Y. — Jordan Spieth doesn’t feel as though his confidence is getting higher. All that mattered was his score getting lower.

Spieth did his best to stay within range of Brooks Koepka at the PGA Championship on Friday by making five birdies over his last 11 holes for a 4-under 66 and his lowest 36-hole score in a major since he won the British Open two years ago.

That was still far from his mind.

“I haven’t been in contention on a Sunday since The Open last year,” said Spieth, who shared the 54-hole lead at Carnoustie and tied for sixth. “And if I’m able to put some good work in tomorrow, I will be in contention on Sunday. And at that point, it will be just more of trying to win a golf tournament. It won’t matter to me what tournament it is.”

It will be proof to Spieth that his struggles over the last year — he even used the words “bit of a slump” earlier this week — are finally turning in his favor. He was at 5-under 135, one shot ahead of Dustin Johnson (67) and Daniel Berger (66) among those who finished early.

Koepka started with a 7-under 63, after becoming the only player to post 63 in the same major twice, and followed that up with a 65 on Friday for a 7-shot lead going into the weekend.

Tiger Woods, playing in the same group as Koepka, started at 2 over and missed the cut by one shot.

Spieth has been showing signs of making progress, only to be done in by one round or a nine-hole stretch. It looked as though that might be the case Friday when he made bogey from the right rough on the 15th and bogey from the left rough on the 16th, putting him 1 over for his round. The key moment was a 6-iron to 8 feet for birdie on the par-3 17th, mainly because it got him back to even after the toughest stretch.

“My goal in turning was try and get to a few under for the championship,” Spieth said. “You don’t expect Brooks to fall at all, so I thought I needed to be within five or six or seven to feel like I had a chance on the weekend.”

He was helped by his tidy short game. Spieth used his putter only 13 times over the last 11 holes, making five birdies and four par saves, only from about 12 feet after finding a bunker on the par-3 third.

Spieth did enough to believe the worst days of his slump are behind him.

It was only in the last few weeks that he felt comfortable enough to return to a familiar philosophy: aim small, miss small.

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

And the putting looks as strong as ever. So when someone suggested Spieth looked freer than he has lately, he smiled and said, “When you’re making everything you look at, anybody is going to walk around feeling pretty free.”