Jeff Overton claimed the lead at the Frys.com Open with a seven-under-par 64 in the first round of the new 2013/14 PGA Tour season.
There was little indication of what was to come from Overton as he parred the first seven holes, but a birdie at eight and an eagle at the par-five ninth kickstarted his round.
Further birdies at 12, 13, 17 and 18, while remaining bogey-free, then put Overton a shot clear of Brian Harman and two ahead of third-placed Kyle Stanley.
"It was just one of those days that it went my way at the end," Overton told pgatour.com.
Harman, 26, mixed eight birdies with a couple of bogeys in his round.
And he hoped the new season - which commenced just four days after the previous one ended - would bring about a turn of fortunes.
"Last year was a grind," he said. "I really didn't play very well at all in stretches. I played well a couple of times, played well enough to keep my card, thank goodness.
"It was just really tough with the year being so short. I feel a bit more freed up this year."
Jason Kokrak headed a group of six men on four under, alongside among others South Korea's Charlie Wi, the only non-American in the top nine.
Defending champion Jonas Blixt of Sweden was two under, in a big group which also included Vijay Singh and Davis Love III, with England's Brian Davis a shot behind them on one under.