Fredrik Jacobson, Stuart Appleby, Rory Sabbatini and Brett Quigley are knotted in second place at 6-under-par 66 at Quali Hollow Club.
Tiger Woods returned to action for the first time since the Masters and posted his first bogey-free round of the 2004 season, a 3-under-par 69. That puts him in a tie for 16th place.
Even with Woods returning to action, back-to-back winner on tour Vijay Singh in the field and Masters winner Phil Mickelson teeing it up, the story on Thursday was Triplett.
Triplett opened on the back nine and tallied his first birdie at the par-4 11th. His round really took shape at the par-5 15th. Triplett holed out for eagle from 70 yards and went to 3 under on his round.
'That was exciting,' admitted Triplett.
He dropped a shot at the next hole but reached the top of the leaderboard with his play on the front nine.
Triplett birdied three of his first five holes on his second nine, then holed a clutch 10-footer to save par at the par-3 sixth. Triplett got up and down for birdie from behind the green at the par-5 seventh and hit a miraculous approach after a horrible tee shot at No. 8. He missed the fairway by almost 40 yards but hit a wedge to 6 feet and made back-to-back birdies.
Triplett's record-setting round continued at the ninth. He sank a 45-foot birdie putt, through a swale and up a ridge in the green for to polish off his round of 64.
'It just kind of felt like my day towards the end of the day,' said Triplett. 'I had hit a number of good shots and was playing nice golf. I feel comfortable out here. That's not to say I didn't hit some poor shots or struggle at times.'
Triplett broke the previous record of 66 set in last year's inaugural event by Nick Price and 2003 winner David Toms.
Jacobson, Appleby and Sabbatini were all bogey-free in their rounds on Thursday. Quigley mixed an eagle, five birdies and a bogey in his opening round to stake his claim to second place.
'I think with the wind gusting, if the wind can gust a little bit here, I think it can become a lot more difficult,' said Appleby. 'Today was the day where I think you can shoot that sort of score. I don't see it getting any easier, though.'
A total of 57 players broke par and 28 of those went below 70.
Among those were 2003 Masters champion Mike Weir. He shot a 5-under-par 67 and was tied for sixth place with Notah Begay III, Heath Slocum, Cameron Beckman, Jay Delsing and Luke Donald.
Singh, who the Houston Open and HP Classic of New Orleans in back-to-back Mondays, bogeyed his final hole to shoot a 68. Mickelson, who was one of the runner-ups to Singh in New Orleans, carded a 2-under-par 70 and is tied for 29th place.
Toms, who quadruple-bogeyed his final hole last year but still won, struggled in the opening round of his title defense. He shot a 3-over-par 75 and is tied for 126th.