Seamus Power birdied his final two holes to keep himself in the mix heading for the weekend at the American Express in California.
The Waterford man had opened with a seven-under-par 65 on Thursday that left him three off the lead, but things were a little more laboured in his second round.
He got to the turn on level par after two birdies were offset by a couple of bogeys, having started on the 10th hole.
Power picked up momentum with birdies on the par-four first and the par-five fifth, and though he gave one back on the sixth, a strong finish hoisted up to ten-under overall, four shots off leaders Patrick Cantlay and Lee Hodges.
Cantlay survived two bogeys over his final nine holes to card a four-under 68 and hold a one-stroke lead.
The reigning FedEx Cup champion moved to 14-under for the week, leading Tom Hoge by one shot. A five-way tie for third at 12-under includes Will Zalatoris, who fired an 11-under 61.