Ryan Moore might have missed out on Ryder Cup selection, but the American fired a 10-under par 61 to take the first round at Summerlin on Thursday.
Course record: Ryan Moore
One shot further behind on nine-under is Zimbabwean Brendon de Jonge, while fellow Americans Tim Herron and John Huh are on eight-under, a further shot adrift.
Starting his round at the 10th, the 30-year-old American was seven-under after eight holes and nearly reached the turn at nine-under when his approach shot hit the flag, but rolled too far away, forcing him to two-putt.
On a course set up for low-scoring , his only dropped shot came at the 17th - his eighth hole - but he birdied the next to regain some of his lost momentum.
"It didn't feel like a great round early," Moore commented after his round.
"I did get off to a nice start. I birdied 11, 12, 13, and then eagled 15. But it wasn't just perfect, perfectly sharp, hitting it right where I'm trying to every single time.
"I was just hitting good, solid shots and converting.
"Then on 18, I was seven under going into that hole, and I holed it out and bounced off the pin to about 40 feet.
"That's when it was like, 'Oh, I guess I'm playing pretty good today'.
"So it was at that point obviously I felt pretty good making the turn shooting 29. I was just trying to keep doing what I was doing. That was just simply out it in the fairway, give myself chances with my wedge and nine-iron, and I knew I was going to convert some of those chances."
On a day perfect for low scores, De Jonge, Huh and Herron didn't drop a shot between them.
Tied for fifth, another shot behind the American duo is Chris Kirk, Justin Leonard and Sweden's Jonas Blixt on seven-under.
Scotland's Russell Knox - the leading Briton is part of a group of players which include former world one Vijay Singh.
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