PEBBLE BEACH -- Hunter Mahan, shot a 6-under-par 66 at Pebble Beach Golf Links to gain a share of the early clubhouse lead with Russell Knox at the AT&T Pebble Beach National Pro-Am.
Knox, a 27-year-old non-winner on the PGA Tour, shot a 6-under par 64 at Monterey Peninsula Country Club. Five players were only a stroke behind on a tight first-round leader board.
Mahan started fast, scoring birdies on five of the first eight holes.
Knox, from Jacksonville, Fla., made eight birdies and two bogeys in forging his lead, but about half the field was still out on the three Monterey Peninsula courses. His best-ever finishes on the PGA Tour have been two ninths, both accomplished last year.
Five players who had completed their rounds were one stroke behind Mahan and Knox. They were Matt Every and Ted Potter Jr., both of whom shot 5-under 67s at Pebble Beach, 21-year-old South Korean Seung-Yul Noh, who shot 5-under 67 at Spyglass Hill, and Greg Owen and Ryuji Imada, who shot 5-under 65s at the par-70 MPCC course.
England's Lee Westwood was another shot behind after shooting a 4-under 68 at Pebble.
Defending champion and four-time winner Phil Mickelson was 2-under at MPCC with two holes to go.