American Ryan Palmer is the lone leader going into the third round.
Palmer finished eagle-birdie on the North Course at Torrey Pines for a five-under 67, taking him to 11-under for the tournament.
The American holds a slim one-shot lead over in-form Spaniard Jon Rahm, the defending champion who birdied two of his last three holes on the North for a 66.
Leading Kiwi golfer Danny Lee has slid down eight places to a share of 23rd but remains in contention in San Diego.
Lee mixed three birdies with two early bogeys to card a second-round 71. The 27-year-old is four-under for the tournament, seven strokes behind Palmer.
The Kiwi appears to have regained his form after missing the cut in his previous three efforts on tour.
Lee lost his spot as the top Kiwi in the world rankings this week after dropping to 125th, three spots behind compatriot Ryan Fox.
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