South Korea's Sungjae Im matched the best score of the day, a 7-under-par 65, and grabbed the lead at the midpoint of The American Express in La Quinta, Calif.
Im thrived Friday at PGA West's Stadium Course to end the day at 11-under 133. He holds a one-shot advantage over first-round leader Brandon Hagy as well as Tony Finau, Canada's Nick Taylor, Mexico's Abraham Ancer and South Korea's Si Woo Kim.
Hagy (2-under 70) and Taylor (66) played the Stadium Course in the second round. Finau (6-under 66), Ancer (65) and Kim (68) played PGA West's Nicklaus Tournament Course.
Doug Ghim (68 at the Nicklaus Tournament Course), Italy's Francesco Molinari (66 at the Nicklaus Tournament Course) and Argentina's Emiliano Grillo (66 at the Stadium Course) share seventh place at 9-under 135.
After the full field played each of the courses on Thursday and Friday, the top 65 and ties (which turned out to be 72 players) advanced to compete at the Stadium Course on both Saturday and Sunday.
Among those who missed the cut were Patrick Reed (68-75 for 1-under 143), Brooks Koepka (72-71 for 1-under 143), and last week's winner of the Sony Open in Hawaii, Kevin Na (75-69 for even-par 144). Tournament host Phil Mickelson parred all 18 holes Friday -- a first for him in his 2,201 career rounds -- and missed the cut at 2-over 146 (74-72).
Im, 22-year-old who earned his first PGA Tour win last March at the Honda Classic, played a bogey-free round.
"I'm pretty satisfied with how I played all of my shots," Im said. "Speaking of putting, I started drawing a line on the ball as I visualize my putts, and that seemed to work pretty well today."
Finau chipped in at No. 4 for one of his seven birdies, and he had just one bogey.
"As we know in this game, it's going to come down to scoring and come down to putting, especially on this type of golf course," Finau said. "I don't think you're going to hit too many balls out of bounds -- you might hit some in the water -- but ultimately the game comes down to who is going to make the most putts on the weekend, and hopefully that's going to be me."
Taylor produced six birdies and no bogeys Friday, running off three consecutive birdies before closing with a par. Last week, he was the 36-hole leader of the Sony Open before winding up tied for 11th.
Ancer, looking to improve on a runner-up finish in The American Express last year, also avoided bogeys throughout his Friday round.
Kim was just 1 under on the front nine before he birdied four of the first six holes on the back nine. He then finished par-bogey-par.
Hagy's up-and-down round featured five birdies and three bogeys.
--Field Level Media