Sahith Theegala fired an eight-under-par 64 to take the first-round lead at the PGA Tour's Sanderson Farms Championship in Mississippi on Thursday.
The 23-year-old from California opened with three straight birdies and never looked back in a bogey-free opening round.
Theegala reached the turn at five under and then added three more birdies on the back nine, including a birdie on the last to take a one-shot lead at the Jackson Country Club.
Nick Watney and Harold Varner III were a shot behind after opening with seven-under-par 65s.
Three players - Canada's Roger Sloan, South Korea's Kim Si-woo and Kurt Kitayama of the United States were tied for fourth on six under.
This week's tournament is taking place with a depleted field, with most of the stars involved in last week's Ryder Cup opting to skip the event.
Spain's defending champion Sergio Garcia, the only player in the field who played the Ryder Cup last week, opened with a two-under-par 70 to finish the day tied for 50th.
Garcia was disappointed after struggling to generate low-scoring momentum over a round that included two birdies and 16 pars.
"A little bit sweet and sour, I guess," is how Garcia summed up his round. "Very happy about not making bogeys, obviously that's always a very positive thing, first round of the season bogey-free, very proud of that.
"But at the same time I feel like I drove the ball quite well and didn't take advantage of it.
"Didn't hit my irons badly, but I just didn't hit them close enough and I was always pretty much all day in that 15 to 25 foot range and hit some really good putts that looked like they were going to go in, and didn't."