Dustin Johnson birdied three of his final four holes to grab a one-shot lead at the halfway stage of the weather-affected Genesis Open.
The US Open champion, who could move to world No 1 this week with a victory, fired a second successive 66 to edge ahead of nearest challengers Pat Perez and Cameron Tringale.
Nearly seven hours of play was lost on Friday due to storms in California, with the second round delayed by a further two hours on Saturday to clear up the course.
Resuming two strokes adrift of overnight leader Sam Saunders, Johnson made a two-putt birdie at the first and holed a 35-footer at the fourth to grab a share of the lead.
Saunders also birdied his opening hole but then posted five bogeys in a seven-hole stretch along the front nine, while Kuchar briefly tied for the lead after following a first-nine 33 with an eagle-three at the first.
Johnson’s run of pars ended when he drained another long-range putt at the 15th, before a kick-in birdie at the 17th moved him two clear of the chasing pack.
The world No 3 rolled in a 20-footer at the last to get to 10 under, before Perez birdied four of his final six holes to reduce the gap to one.
A slamdunk birdie at the last closed a round-of-the-day 64 for Tringale to also lift him in to the share of second, with one-time leader Jhonattan Vegas another two strokes back with Patrick Rodgers and J.T Poston.
USA Ryder Cup stars Ryan Moore and Brandt Snedeker were among the high-profile names to miss the cut, while Hideki Matsuyama made an early exit following a nine-over 80 on Saturday.
Seventy-one players made it through on even par or better, with tournament officials still confident of getting 72 holes completed without the need of a Monday finish.
Watch day four of the Genesis Open live on Sunday from 6pm on Sky Sports 4 – your home of golf
