Jordan Spieth birdied his last hole to retain a one-stroke lead heading into the final round at the Charles Schwab Challenge.
Jason Kokrak had joined 2016 champion Spieth atop the leaderboard before the latter stepped up to birdie the 18th in the third round at Colonial Country Club on Saturday.
Former world number one Spieth signed for another four-under-par 66 to remain the player to beat ahead of Sunday's finale in Fort Worth, Texas.
Spieth, whose 40-hole bogey-free streak ended at the par-four fifth hole, is eyeing his second PGA Tour title of the season, having ended his four-year trophy drought via last month's Texas Open.
A three-time major champion, Spieth only dropped two shots as he finished with six birdies, including three across a flawless back nine to be 15 under through 54 holes.
Fellow American Kokrak stayed within a shot of Spieth courtesy of his third-round 66.
Sergio Garcia – the 2017 Masters champion and 2001 Charles Schwab Challenge winner – is five strokes off the pace following his two-under-par 68.
Ian Poulter (64) surged up the leaderboard, improving 26 positions to be tied for fourth at eight under alongside Sebastian Munoz (70).
Former world number one and 2013 U.S. Open champion Justin Rose (69) is 10 shots behind Spieth, defending champion Collin Morikawa is two strokes further back after his 72, while Justin Thomas (71) slipped to 46th – 14 shots adrift.