Vijay Singh claimed a share of second place as Bo Van Pelt carded a blemish-free four under par 67 to lead by one at the end of the first round of the AT&T National in Bethseda, Maryland.
Van Pelt claimed a birdie at the par four first, his tenth, and added two birdies to lead by one from Singh, Brendon de Jonge and Jimmy Walker.
Low scoring proved tough on a hot day, and with only 22 men going under par it was an impressive start by Van Pelt.
The American was particularly pleased with his putting.
"That's improved the most," Van Pelt told www.pgatour.com. "I've stuck with one putter since last year in the fall, and it's probably the longest stretch I've done that since I was a kid."
Van Pelt enjoyed a tough test on what he felt was as difficult a course as he had played this year.
Asked if he'd seen a tougher course in 2012, he said: "Probably not. I would say Olympic maybe it was hard in a different way, but that's all you want out there right now for sure."
Veteran Fijian Singh carded seven birdies in an erratic 68, finishing the day a stroke ahead of Billy Hurley III, Pat Perez and Jason Day.
England's Greg Owen led the European challenge on one under in a group of 15 players tied for eighth which also included defending champion Nick Watney, Stewart Cink and US Ryder Cup Captain Davis Love III.
Tiger Woods was one over, as was Scotland's Martin Laird.