Keith Mitchell built a commanding five-shot lead entering the weekend following another impressive round at The CJ Cup.
Mitchell carded an eight-par-under 64 to soar to the top of the leaderboard after the second round in Nevada on Friday.
The one-time PGA Tour champion dazzled with a first-round 62 and the American backed that up by holing an eagle, seven birdies and just one bogey.
Mitchell is the player to beat at the halfway stage after setting a new tournament 36-hole record at 18 under.
"I spent a lot of time in the last few days leading up to this tournament working hard on my game and it's showing," said Mitchell, whose lone victory came at the 2019 Honda Classic.
"I'm very thankful for that. Just shows you that hard work pays off as long as you're doing the right things."
Former world number one Jordan Spieth (65), Kim Seong-hyeon (63), Harry Higgs (67) and Adam Scott (63) are Mitchell's nearest challengers at 13 under heading into Saturday's penultimate round.
Spieth made his move late in the day with four birdies in five holes to earn a share of second position, while another former world number one – Scott – enjoyed a red-hot finish to his day after going birdie-birdie-eagle-birdie-par-birdie-eagle in his last seven holes.
Scott's second round included a career-high 14 one putts, having played the final seven holes eight under – his best seven-hole stretch to close a round on Tour.
Four-time major champion Rory McIlroy (67) shot his second round in the 60s to move into a tie for 19th position, nine shots behind Mitchell – alongside Abraham Ancer, who made an albatross on the par-five 14th hole, while Masters winner Hideki Matsuyama (70) and two-time CJ Cup champion Justin Thomas (67) are a stroke further back.
American star Brooks Koepka lost ground following his two-under-par 70 which left him seven under, while Dustin Johnson bounced back from his opening-round 74 with a 66.