Patrick Cantlay broke the course record with a bogey-free, 11-under 60 on Saturday to take a share of the lead at 19-under in the Shriners Children's Open.
"I was really happy with today. I played great. Had a bunch of looks and made most of them. Took advantage of the par-5s and the drivable 4, and that's what you have to do around this place."
He had a chance to close with a 59 but missed his birdie putt on the final hole.
"I had like 120 in the fairway and it was a perfect spot and I hit a big sand wedge and I thought I hit it high enough and it took a huge bounce when it landed. Then the putt probably carried a bit too much speed, and just missed it a little high.
"I hit good putts all day today. You can't make every single one as much as you'd like to. I'm very happy with how I played, and I'm in a good spot going into tomorrow."
The American matched his low score on the PGA Tour but it was his first as a pro, he previously shot 60 at the 2011 Travelers Championship as an amateur.
South Korean Tom Kim played a bogey-free 62 for a share of the lead.
"I've played really solid today. I took care of what I really needed to take care of on this golf course and just needing a good round to give myself a chance on Sunday really because I'm really happy with myself just keeping it tight," said Kim.
"This course is very, very scorable so you've got to play good golf. You've got to make a lot of birdies. Anyone is in this really. It's not just me and Patrick. There's a lot of guys who can still play well and win it. Just kind of stick to my own game plan. I've been doing well for the past three days, and just hopefully have one more good round on Sunday and have a good finish."
Overnight leader Mito Pereira of Chile carded a 67 and moved down into a share of third place at 16-under alongside American Matthew NeSmith who shot a bogey-free 63.
South Koreans Sungjae Im (63) and S.H. Kim (64) share fifth place at 15-under.
It was a low scoring day at TPC Summerlin with nine players firing a 64 or lower and the course average was 67.9.