Brendan Steele fired the lowest round of his PGA Tour career to take a two-shot lead into the final day of the Sony Open in Hawaii.
Steele, who lost out in a playoff to Cameron Smith in last year's contest, carded a bogey-free 61 at Waialae Country Club to get to 18 under and move ahead of the chasing.
Kevin Na matched Steele's 61 to sit in tied-second alongside Sentry Tournament of Champions runner-up Joaquin Niemann, with Charley Hoffman a further stroke back and one of five players sharing fourth on 15 under.
"I feel like I'm swinging really well and my course management is very good," Steele said. "I'm excited for the challenge tomorrow. I know it's going to be really tough. Guys are coming after me, but I'll just do my best and hopefully it will be enough."
Heading into the weekend three off the lead, Steele rolled in a 20-footer at the first and holed from half the distance at the sixth for the first of four birdies in a five-hole stretch around the turn.
Steele converted from 15 feet at the 12th and struck his approach to tap-in range at the 15th, with the world No 114 then following a 25-foot birdie at the 17th by picking up another shot at the par-five last.
Na threatened a '59 round' when an eight-foot eagle at the ninth and four straight birdies from the 11th took him to eight under with four holes to play on the par-70 layout, only to see his hopes ended after miss opportunities from inside 10 feet at both the 15th and 17th.
A final-hole birdie took him to 16 under and set the initial clubhouse target, which Niemann matched after closing out his blemish-free 63 with a birdie-eagle finish in calm conditions.
Hoffman is three strokes back with Peter Malnati, Stewart Cink, Russell Henley and Chris Kirk, while a third-round 68 leaves overnight leader Nick Taylor four off the pace alongside Marc Leishman, Daniel Berger and Keith Mitchell.
The threat of heavy rain on Sunday afternoon and further bad weather on Monday has seen the PGA Tour bring the tee times forward by two hours for the final round, with play due to finish by 3pm local time (1am GMT).
Who will win the Sony Open? Watch the final round live on Sunday from the earlier time of 9pm on Sky Sports Golf!