Defending champion Dustin Johnson posted a 64 to lead the field after the opening round of the AT&T Pebble Beach National Pro-Am on Thursday.
The 25-year-old Johnson carded 10 birdies in total, including a spectacular run of five in a row, to finish the day on eight-under-par -- one stroke ahead of compatriot JB Holmes and Korean KJ Choi -- with Charley Hoffman alone on six-under-par.
The tournament is played over three separate courses, with the leading trio all starting at Pebble Beach.
Hoffman also carded a 64 -- including five birdies and an eagle -- but he opened his round at the par-70 Monterey Peninsula.
Meanwhile, former British Open champion David Duval was among three players who posted rounds of 67 at Spyglass Hill, the same course where world number two Phil Mickelson carded a two-under-par 68.