Justin Thomas and Ryan Moore both carded six-under-par 67s to take a one-shot lead at the SBS Tournament of Champions on Friday.
Thomas and Moore, who are on 12-under, are just ahead of Patrick Reed and overnight leader Jimmy Walker in third place on 11-under.
Meanwhile, world number one Jason Day is in a tie for 11th on seven-under, while defending champion Jordan Spieth is seven strokes adrift of the lead in a tie for 19th.
Thomas kicked off his round with a bang as he made a hat-trick of birdies from the third to fifth. Despite cooling down for remainder of the front nine, he began to heat up again on the back nine as he made four birdies and a bogey.
Moore made a mediocre start to the second round as he made two birdies and a bogey on the front nine. However, it was a much different story on the back nine as he began by sinking a 27-foot putt at the 12th before proceeding to make four more birdies.
Reed surged up nine spots on the leaderboard on Friday as he began his round of 65 with three successive birdies from the third to fifth. The 26-year-old shifted his game to the next level on the back nine, where he made five birdies.
Walker, meanwhile, was unable to keep hold of the lead as he fired a three-under-par 70, which consisted of four birdies and a bogey.
Day recorded a four-under-par 69, which included five birdies, one of which came via a 23-foot putt at the 12th, and a bogey.
As for Spieth, he bounced back from his opening round of 72 by registering a 69 on Saturday. The 23-year-old was in brilliant form for most of the day as he made nine birdies, but a lot of his hard work was undone through a double bogey at the par-three eighth and a triple bogey at the par-four 17th.