Justin Thomas and Ryan Moore produced final-hole birdies to lead at the halfway mark of the SBS Tournament of Champions.
The American duo top a congested leaderboard at 12 under after shooting six-under par 67s in the second round at Kapalua Resort in Hawaii on Friday.
Thomas, who has two top-four finishes - including a win - in his past three starts, mixed seven birdies with a bogey.
Like Moore, whose only blemish came at the par-three second hole, he birdied the 18th.
The pair are a shot ahead of Patrick Reed, the American who surged into contention with a 65, and overnight leader Jimmy Walker (70).
The big guns are still sitting well back.
World number one Jason Day (69) is tied for 11th at seven under, with Dustin Johnson (70) alongside him.
Defending champion Jordan Spieth got on a roll with five straight birdies in the middle of his round, but a triple bogey at the 17th hurt him. The American is at five under.
Jason Dufner (68) is outright fifth at 10 under, a shot ahead of Japan's Hideki Matsuyama (68).
Tony Finau (68), Fabian Gomez (68), Daniel Berger (70) and Jim Herman (71) are a shot further back.