Scotsman Martin Laird built on his overnight lead after carding a three-under-par 68 in the third round at the Phoenix Open on Saturday.
Laird enjoyed a two-stroke buffer at the close of play on Friday and the 32-year-old extended that advantage by a shot at TPC Scottsdale.
A bag of six birdies and three bogeys saw Laird to 13 under through 54 holes in Scottsdale, Arizona.
The three-time PGA Tour champion, whose last win came at the Valero Texas Open in 2013, is three strokes clear of Japan's Hideki Matsuyama and American pair Brooks Koepka and Zach Johnson.
Francesco Molinari provided one of the highlights of the day, a hole-in-one at the 163-yard par-three 16th.
Delighted fans went wild after the Italian's shot, throwing beer cans onto the course.
Following on from his second-round 66, Laird made a nervy start on the penultimate day after bogeying the par-four first.
Laird regrouped and sunk back-to-back birdies at the third and fourth holes, though he dropped a shot at the fifth.
He approached the turn with a birdie at the ninth under his belt, which was followed by another three on the back nine, including a close-range putt at the17th having sent his short wedge within four feet of the hole.
Matsuyama, Koepka and Johnson are within touching distance of the Scot.
A blemish-free eight-under 63 helped Matsuyama power up the leaderboard, climbing 25 spots.
Matsuyama had eight birdies throughout the third round, which was capped by four in succession to end his day.
Koepka enjoyed a similar rise up the standings - improving 18 positions - courtesy of his faultless third-round 64 that was set up by six birdies on the back nine.
Johnson, meanwhile, produced a four-under-par 67 for a share of second place.
Spanish amateur Jon Rahm (66) and Americans Ryan Palmer (68) and Justin Thomas (69) are four shots off the pace at nine under.
A total of nine players are tied for eighth position heading into the final day of play.
Russell Henley (65), Russell Knox (65), Kevin Chappell (65), Molinari (64), Robert Streb (69), Angel Cabrera (69), Bubba Watson (69), Ryan Moore (69) and Daniel Berger (71) are all eight under through 54 holes.