ATLANTA – The day-to-day vagaries of golf are often used to explain changes in form, but Dustin Johnson’s transformation on Sunday was much more specific.

Johnson pulled away from the field at the Tour Championship with a third-round 64. He owes his five-stroke lead thanks to a post-round session on Saturday with his swing coach Claude Harmon III, one that focused on his driver.

“I felt like I was swinging well. It was just a little bit off, then obviously just the setup was just a hair off,” Johnson said. “What was happening is I was just hitting the driver a little bit towards the toe, and obviously when you hit it off the toe, it does not like to cut. That was really all we did was just fix the setup a little bit.”

Johnson made the fix sound impressively simple; the statistical results were dramatic. After hitting just seven fairways through his first two rounds, he matched that mark through 13 holes on Day 3. He also picked up more than a shot in strokes gained: off the tee on Sunday, and he remains second in the field in driving distance (310.7-yard average).

Dramatic turnarounds are becoming Johnson’s thing. He’s 72 under par in his last five events (counting three rounds at East Lake), but prior to that he withdrew from the 3M Open after an opening 78 and missed the cut at the Memorial with back-to-back rounds of 80.

“It wasn't hard at all. I mean, I don't know about you, but I hit bad shots all the time,” he said of his missed cut at Muirfield Village. “Everything was compounded a little bit. I just wasn't swinging very good. My mind wasn't in it. Yeah, it was just a lot of bad. But it's real easy to forget. All it takes is a couple good shots and it's gone.”