Kuchar notched seven birdies and no bogeys at Riviera Country Club in Palisades, Calif.
Sergio Garcia carded a 6-under 65 to ending the day alone in second place.
Brandt Jobe fired a 66 for third place.
Rookie James Hahn, David Lynn and Charlie Beljan each carded a 4-under 67 to share fourth place before play was suspended.
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