FARMINGDALE, N.Y. — Brooks Koepka said his “tunnel-vision focus” was key to his success in major tournaments as he held onto his record seven-stroke lead going into Sunday’s final round of the PGA Championship.

Koepka ended the third round on Saturday with the same lead as he started it, combining the strength of tungsten with the precision of a calligrapher in a near-clinical even-par 70 in brilliant sunshine at the demanding Bethpage Black.

“I’m definitely not going to let up, I promise you that,” he said after posting a 12-under 198 total. “I feel confident going into tomorrow. If I can get off to a good start, these first six holes are very scorable.”

Long-hitting fellow Americans Dustin Johnson (69), Harold Varner III (67) and Luke List (69), and Thailand’s Jazz Janewattananond (67) were locked in second place on five under.

The largest 54-hole lead in championship history left Koepka needing only to avoid a disastrous Sunday to retain the title. He has also won the past two US Opens.

“I’m more focused than anybody out there,” Koepka said, when asked why he performs better in majors than regular PGA Tour events.

“I think I’m tunnel-visioned. My focus probably goes up, I don’t know, tenfold of what it does in a tour event.”

The engraver is not quite ready to etch Koepka’s name into the Wanamaker Trophy just yet with the largest PGA Championship comeback after 54 holes was American John Mahaffey coming from seven behind to beat Tom Watson in a playoff in 1978.

Johnson has not given up hope of a similar fightback.

“It’s going to take something special to catch Brooks but it’s definitely doable on this course because it’s so difficult,” said Johnson.

List, who has yet to win PGA Tour title, was less optimistic.

“I think we’re all pretty much playing for second,” he said. “It seems like that hasn’t been said since Tiger (Woods) back in his heyday.”

Koepka was relentless on Saturday, smashing his drives more than 300 yards and hitting soaring iron shots that honed in on the pins.

He limited his damage to three bogeys, using his power to muscle his ball out of the lush rough on the odd occasion when he strayed from the fairway.

His rivals did not play badly, but the damage had been done in the first 36 holes.

They simply had too much ground to make up with their cause made all the more difficult by the rough that gobbled up errant shots, while the wind whipped up over the final hour of play.

Johnson had six birdies, but littered his card with five bogeys, while List bogeyed the final two holes.

Koepka, however, gave his rivals a tip on how to deal with their final day chase.

“It’s grind it out, suck it up, and move on,” he said.

“You’re going to make a lot of mistakes; it’s a major championship. You know that’s going to happen and guys have a hard time letting that go.” — Reuters