Text messages in the middle of the night with his coach are part of a round-the-clock obsession Jason Day has with his new swing that has launched him into the lead at the Wells Fargo Championship.

Day, whose struggles with his game have resulted in a world rankings plummet to No.127, fired a brilliant 63 at the par-70 TPC Potomac to top the leaderboard at seven-under-par.

He’s one stroke ahead of Joel Dahmen (64), while Matt Wolff, Denny McCarthy, Aaron Rai, and Callum Tarren (65) were at five under.

Day has been working with swing coach Chris Como, who once worked with Tiger Woods, for almost three years and has been grooving a swing that is steeper and produces a left-to-right shape. He spent the majority of his career hitting a high draw.

The revamped swing was firing on all cylinders on Thursday as former world No.1 Day hit 13 of 14 fairways and 13 of 18 greens. He mixed eight birdies with a long bogey and missed a short birdie putt on the 18th for a 62.

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“There is a lot of behind the scenes work with Chris,” Day said after his round. “I think about the golf swing in the morning, during the day and at night. There have been conversations at midnight (with Como) just because I have had an idea or a feel in the swing. I’m obsessed with it.”

Heavy rain and inclement weather are forecast for the remaining three rounds at the Wells Fargo. Day compared that forecast, when combined with the tricky tee shots and thick rough at TPC Potomac, to US Open conditions. He was once seen as a US Open specialist and finished second at the 2011 US Open at Congressional across the road from TPC Potomac.

Day welcomed a tough conclusion to the Wells Fargo.

“We’ve got some weather coming in, so I feel like we’re going to go into grind mode over the next few days, which I typically like. It’s going to be difficult and I have to just focus on myself and just do whatever I can to shoot a low one.”

Cam Davis (67) was next best of the Australians, while Marc Leishman (68) was two under. Cam Percy (70), Brett Drewitt (72), Matt Jones (73) and Aaron Baddeley (74) rounded out the Australian contingent at TPC Potomac.