England's Matt Wallace birdied five of the first six holes on his way to grabbing the early lead in Thursday's first round of the PGA Tour CJ Cup Byron Nelson tournament.
The 34-year-old from London fired a bogey-free eight-under-par 63 at TPC Craig Ranch in McKinney, Texas, for a one-stroke lead over Sweden's Alex Noren, Canada's Taylor Pendrith and American Chesson Hadley with late starters still on the course.
"It was great. Really solid day," Wallace said. "Got off to a great start. Three birdies to start any tournament is nice. Just a really solid round of golf."
It was the lowest PGA Tour round for Wallace, a four-time European Tour winner whose only PGA triumph was at last year's Puntacana Championship in the Dominican Republic.
"I knew something like this was coming," Wallace said. "I know I'm building into a good stretch."
Wallace found a fairway bunker off the first tee but blasted his approach just inside 13 feet and sank the birdie putt, then dropped his approach inside three feet from the hole at the second to set up another birdie.
He landed his approach inches from the hole at the third to set up another birdie, then birdied from inside three feet again at the fourth and fifth holes.
Wallace added birdie putts from six feet at 11, four feet at 14 and a tap-in at the par-5 18th hole.
"Drove it nice for the most part," Wallace said. "Few times I was in the semi-rough with a bid of mud on the ball which can cause a little bit of doubt. Top up on those, focus on hitting my tee shots well for the next few days and we'll be in good shape."
Australia's Jason Day, the defending champion, opened on 66.
"I feel like my game suits it pretty nice around this course," Day said. "I think overall the average winning score is 22-under around here. You kind of have to shoot 5-, 6- a day, somewhere in that region. So it's good. Kind of on par right now."
Three-time major winner Jordan Spieth, who can complete a career grand slam by winning the PGA Championship in two weeks, shot a 68.
"I just played the easy holes poorly," Spieth said. "Played the par-5s 1-over. That was kind of the story of the day. The par-5s you need to be 2.5-under out here each day. I'll have to make that back up."