Jason Day leads the Wells Fargo Championship

Jason Day says he’s “obsessed” with polishing his new swing and increasing his results, even if he never returns to No. 1 in the world, three years and 364 days after his last victory.

Day blasted a 7-under 63 in the opening round of the Wells Fargo Championship on Thursday, leaving little opportunity for improvement.

With rain, wind, and uncharacteristically chilly temperatures anticipated until Sunday, Joel Dahmen was a shot back on what should be the finest day for scoring at TPC Potomac at Avenel Farm.

“Obviously, we’ve got some weather coming in, so I think we’re going to go into grind gear over the next several days,” Day said. “It’s going to be challenging.”

Day, 34, has been working on a swing with teacher Chris Como to preserve his chronically achy back, and he says it feels solid with every club except the driver.

In 2015-16, he won eight times in 15 months, including the PGA Championship and the Players Championship.

Day said, “I think about the golf swing in the morning, the golf swing during the day, and the golf swing at night.”

“I’ve had talks with Chris at 12 a.m. just because I’ve had an idea in my head and a certain vibe and feeling.”

Day’s most recent victory came at Quail Hollow in this tournament. Because the Presidents Cup is being held in September, the Wells Fargo has relocated to the Maryland suburbs of Washington.

Day, who hit five of his eight birdies from inside 10 feet on Thursday, would be welcomed back by the International squad at that event. With a chip-in on the par-4 15th hole, the Australian took the lead.

“The difference between today and when I was No. 1 in the world is that I had all the confidence in the world, especially on the greens, even though my technique wasn’t as sharp as it is now.” Day stated, “That is always the goal.”

Matthew Wolff, Denny McCarthy, Aaron Rai, Callum Tarren, and Paul Barjon, all PGA Tour rookies, were two strokes back. Rory McIlroy, the field’s top-ranked player at No. 7, shot a 67 that was up and down.

The 23-year-old long-previous hitter’s two competitive rounds were an 81 and a 78 at the Masters, where he finished below every 60-something prior champion in the field.

He lost every ball in his bag during a casual round at his home club a few days ago.

“I can go out and shoot 90 tomorrow and put a check mark on this week and say that I’ve evolved as a person and as a player, and that’s all I really care about right now,” Wolff said.

“It’s funny, to be honest, because I’m not here to win a golf tournament; I’m here to have fun.”

Dahmen relished his swift ascent to the top of the standings. He gazed at the scoreboard behind the green while waiting for playing companions Patrick Reed and Jason Dufner after hitting a 7-iron from 173 yards to 7 feet on the par-4 eighth hole.

He then holed the putt to get to six under par.

“It’s nice to have my name up there.” It’s something for which we all strive, right? “I believe it’s fantastic to have a little bit of pressure in the first round,” Dahmen added.

On the back nine, Dahmen’s putter cooled, but he finally made another birdie when he narrowly missed an ace at the par-3 17th.

McIlroy’s first major blunder came on the par-4 fourth, when his tee shot started too far left and drew into the water.

Double bogey was the result of a penalty drop and a poor chip, but he bounced back with birdies on the next two holes.

“Walking off the green, I told myself that if I could just get back to 3 under for the day by the end of the day after that, I’d be very satisfied,” McIlroy said.

On the par-4 sixth, Rickie Fowler blasted two shots into the right-side marshes, then holed out from 134 yards to avoid bogey.

In a round of 66 that he described as “unusual,” he hit driver to 11 feet for eagle on the 305-yard, par-4 13th.

“There were a couple that were a touch off and cost me a little bit early in the round, but other than that, a lot of nice stuff,” said Fowler, who has plummeted to 146th in the world due to swing modifications. “I’m quite pleased with today.”