Los Angeles - Kevin Na equalled his career-low round with a 10-under par 61 on Saturday to take a two-stroke lead over fellow American Patrick Cantlay in the PGA Tour Shriners Hospitals For Children Open.
On a day when plenty of players were going low on TPC Summerlin in Las Vegas, Na produced another strong performance on the greens in following up his second-round 62.
His 22-under total of 191 was a 54-hole record for the tournament, a home fixture for the South Korean-born American who won the first of his three PGA Tour titles in this event in 2011.
"I feel comfortable, I feel confident," said Na, who had 10 birdies without a bogey.
Cantlay, who won at TPC Summerlin in 2017 and finished second last year, kept the pressure on with eight birdies in his first 16 holes.
He faltered at the par-three 17th, where he was unable to get up and down from a greenside bunker, but closed with a birdie at 18 to cap a 63 for 193.
It was a further two strokes back to American Pat Perez, who had an eagle and seven birdies in a nine-under 62 for 195.
"I've still got to keep the pedal to the metal," Na said of the task awaiting on Sunday. "There's a lot of low scores out here. Anybody could shoot eight- or nine-under."
Na started the day in a four-way tie for the lead with Cantlay, Lucas Glover and Brian Stuard.
He opened with birdies at the first and second, but said his biggest putt of the day was a 22-footer to save par at the par-three fifth.
"I had nothing," he said. "I hit it to about 25 feet and made a 25-footer that broke six feet for par."
He rolled in a 20-foot birdie putt at the eighth and a 30-footer at 10. After a 16-foot birdie at 13 and an eight-footer at 15 his five-foot birdie miss at 16 was a shock.
He rebounded quickly, however, closing with back-to-back birdies with putts of 14 and 12 feet.
Stuard and Glover were unable to gain ground, Glover posting a 66 that left him tied for fourth with Sam Ryder on 196 and Stuard finishing six shots off the pace after a 67.
American Tony Finau, among the players hoping from some good results to catch the eye of US Presidents Cup captain Tiger Woods before he makes his last selections for the team for the December match play showdown in Australia, carded a 62 that featured an eagle and seven birdies.
"It motivates me," Finau said of the Presidents Cup. "I'm a little bit disappointed that I didn't make the team. Maybe that's lighting a little bit of a fire in me going into the season."
191 - Kevin Na 68-62-61
193 - Patrick Cantlay 66-64-63
195 - Pat Perez 69-64-62
196 - Sam Ryder 65-67-64, Lucas Glover 67-63-66
197 - Webb Simpson 67-66-64, Brian Stuard 65-65-67
198 - Tony Finau 68-68-62, Denny McCarthy 69-66-63, Brian Gay 65-69-64, Adam Scott (AUS) 66-67-65, Ryan Moore 69-64-65
199 - Luke List 70-66-63, Lanto Griffin 67-65-67