Byrd, a former Clemson standout, seeking his fourth PGA Tour title, had nine birdies and a bogey in perfect scoring conditions in the fourth of five Fall Series events.
Ryuji Imada was a stroke back after 62. He had an eagle, eight birdies and a bogey.
Defending champion Martin Laird (62), Alex Prugh (64), John Senden (67), George McNeill (66) and Nicholas Thompson (66) were two strokes back at 11 under. Ryder Cup player Rickie Fowler (64) topped a group at 10 under, and U.S. teammate Hunter Mahan was 7 under after his 68.
LPGA: In Kuala Lumpur, Malaysia, Mika Miyazato and Jee Young Lee shot 5-under-par 66 and lead after the first round of the Sime Darby LPGA Malaysia event at Kuala Lumpur Golf and Country Club.
Hee-Won Han was a shot back at the tournament, which had a 3-hour delay because of lightning.
Michelle Wie shot 68. She had four birdies and bogeyed the 15th hole after a three-putt. Suzann Pettersen had 69, while Christina Kim, Natalie Gulbis and Katherine Hull all shot 70. Juli Inkster trailed the leaders by five.
Miyazato had five birdies in a bogey-free round. Lee had seven birdies but bogeyed the third and 11th holes.
CHAMPIONS TOUR: The Woodlands, Texas, U.S. Ryder Cup captain Corey Pavin shot 6-under-par 66 for a one-shot lead after the first round of the Champions Tour's Administaff Small Business Classic.
Mark Wiebe birdied three of the final six holes for 67 in a steady round that included five birdies and no bogeys. Two more shots back was Russ Cochran, who had to overcome back-to-back bogeys on Nos. 8 and 9.
Ten other players, including defending Charles Schwab Cup champion Loren Roberts, finished with 2-under 70s.
EUROPEAN TOUR: In Castellon, Spain, Peter Hedblom shot 7-under-par 64 to take a one-shot lead after the second round of the Castello Masters.
Hedblom moved to 9-under 133 and would have doubled his lead if not for a bogey after he missed the green on the ninth hole, his last of the day at Club de Campo Del Mediterraneo.
Three players were tied for second place at 8 under. Gonzalo Fernandez-Castano shot 66, Paul Lawrie had 70 after opening with 64 and teenager Matte Manassero finished with 66.
NATIONWIDE TOUR: In Ponte Vedra, Fla., David Mathis shot 73 and has a two-stroke at the Winn-Dixie Jacksonville Open.
Mathis is at 9-under 273.
Augusta's Scott Parel shot 69 and is tied for 14th, five shots back. Aiken's Kevin Kisner missed the cut after a second-round 69.