Eleven days ago, Brooks Koepka was on the range at Medalist Golf Club in South Florida, working through yet another frustrating range session.

Normally the picture of poise, he flung a club 70 yards behind him. Another club lay in front of him.

“I was pretty heated,” he said.

But it turned out to be a day of practice that fixed Koepka’s swing, and one that may lead to even more history. Poring over swing video with coach Pete Cowen, Koepka learned that 70 percent of his weight was on his back foot at impact – a subconscious move to alleviate pressure on his ailing left knee.

The fix was simple – dropping back his left foot “a hair” – and while watching video from the past two PGA Championships with caddie Ricky Elliott, Koepka noticed that from that position he was able to drive off his right foot and not feel any twinges of pain.

“My feet are usually a little bit staggered from a perfect golf swing, too far left,” he said, “but that’s just how we play. It’s nice to feel comfortable over the ball. I’m starting to see it come out of the right pocket, the right window, and that’s exciting.”

Coupled with an equipment change – earlier this week he switched from a Callaway driver to his old TaylorMade M5 – Koepka is starting to rediscover that old winning form. He tied for second last week at the WGC-FedEx St. Jude Invitational, where he chased eventual winner Justin Thomas all the way to the finish, and then he opened with a 4-under 66 Thursday in his bid to become the first player in nearly a century to win the PGA Championship in three consecutive years.

From posting just a single top-10 this year and facing questions about his form and troublesome knee, the four-time major winner is now oozing with confidence.

“I feel right where I should be,” he said. “I’m excited. I’m ready to play.”