Seamus Power carded a second-round 68 at the The American Express in California, moving him to nine under at the halfway mark, with American duo Blades Brown and Scottie Scheffler tied for the lead on 17-under par.
Starting on the tenth at the La Quinta Country Club, Power birdied 11 and 12 before a run of pars that ended with a bogey at the second.
The Waterford man recovered, however, and picked up shots on three, five and six. He is in a tie for 48th at the halfway stage.
Eighteen-year-old Brown shot an incredible 12-under-par 60 to surge into a tie for the lead alongside the world No. 1.
Brown, playing at the Nicklaus Tournament Course, began with a birdie at his first hole, the tenth, and followed that with an eagle at the next. He rolled in nine more birdies that saw him finish 12 under for his round.
However, missing an eight-foot putt at the last prevented history.
Needing one birdie over his final three holes to set himself up for an elusive round of 59, the teenager delivered three pars instead to just miss out on posting the 16th sub-60 round in PGA Tour history. He also would have been the youngster player in PGA Tour history to achieve it.
World number one Scheffler added a 64 to his opening 63 in a round that contained eight birdies at the same course.
South Korea's Si Woo Kim is a shot further back in third after a 65. Compatriot SH Kim is fourth alongside the USA's Matt McCarthy.
Brown's heroics on Friday were also matched by Andrew Putnam. The 36-year from Washington, who began with a 72, had an eagle at the 11th and ten birdies as he also posted a 60.
This week's field will play the first three rounds at three different courses, with one round at each: the Pete Dye Stadium Course, the Nicklaus Tournament Course and La Quinta Country Club. The cut will occur Saturday after 54 holes, with the top 65 players and ties advancing to Sunday's round at the Pete Dye Stadium Course.
Additional reporting: Reuters
