The 31-year-old, who finished second in the US open in 2009, has struggled so far this season, making just four cuts in 11 tournaments, but he returned to form in fine fashion to lead by one from Boo Weekley and Lucas Glover.
An eagle on the second got the American off to a flying start and, after reaching the turn at two under, he hit six birdies on the back nine to take the lead on eight under.
It came just three days after his wife Suzanne gave birth to the couple's second child, Natalie, and it tied the course record at a wet TPC Louisiana.
"I knew you could attack the pins this morning because of the soft greens," he told www.pgatour.com. "But if you asked me if I thought I would tie a course record, no, I didn't think that when we went out this morning.
"But I've been working my (butt) off and it showed today [Thursday]. It was nice to go out and play a good round. I knew I had some good golf in me, but until you go out and actually shoot it, no one will believe you."
Weekley's blemish-free round of 65 was highlighted by an eagle at the second, while Glover was slightly more erratic, carding two bogeys against nine birdies.
DA Points and Morgan Hoffmann were a shot back further back on six under, while Ernie Els, Rickie Fowler and Charlie Beljan were among 10 players on five under.
England's Brian Davis and Justin Rose led the European challenge, carding four-under 68s for a share of 16th, while defending champion Jason Dufner was two under,
China's Guan Tianlang, who at the Masters became the youngest player ever to make the cut at a major at the age of 14, was level for his opening round, one shot ahead of Denmark's Thorbjorn Olesen, who tied for sixth in Augusta.