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 10th, and added two birdies to lead by one from Vijay 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 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, with England's Brian Davis three over.
Collated first round scores in the USPGA Tour AT&T National, Congressional G & CC, Bethesda, Maryland, United States of America
(USA unless stated, par 71):
67 Bo Van Pelt
68 Brendon De Jonge, Vijay Singh (Fij), Jimmy Walker
69 Billy Hurley III, Pat Perez, Jason Day (Aus)
70 Nick Watney, Seung-yul Noh (Kor), Robert Garrigus, Davis Love III, Greg Owen (Eng), Stewart Cink, John Mallinger, James Driscoll, Charles Howell III, Charlie Wi (Kor), Dustin Johnson, Hunter Mahan, Marc Leishman (Aus), Brandt Jobe, Daniel Summerhays
71 Brendan Steele, Rodney Pampling (Aus), Vaughn Taylor, Beau Hossler, Angel Cabrera (Arg), Jhonattan Vegas (Ven), Harris English
72 Charley Hoffman, Tiger Woods, Gary Woodland, Patrick Cantlay, Blake Adams, Chez Reavie, Martin Laird (Sco), Ryuji Imada (Jpn), K.t. Kim (Kor), Kyle Stanley, Greg Chalmers (Aus), Brian Harman, Kevin Chappell, William McGirt, J.J Killeen, J.B. Holmes, Brendon Todd, John Huh (Kor)
73 Bud Cauley, Erik Compton, Brian Gay, Will Claxton, D.A. Points, George McNeill, Sean O'Hair, Jim Furyk, Andres Romero (Arg), Tom Gillis, Troy Matteson, Johnson Wagner, Ryan Moore
74 Brian Davis (Eng), Rory Sabbatini (Rsa), Bobby Gates, Ryan Palmer, Billy Mayfair, Ben Curtis, Kelly Kraft, Graham Delaet (Can), Ricky Barnes, Bob Estes, Trevor Immelman (Rsa), Roberto Castro, Hunter Haas, Cameron Tringale, Josh Teater
75 Martin Flores, Matt Bettencourt, Justin Leonard, Chad Campbell, Boo Weekley, Jordan Spieth, Chris Stroud, Tim Herron, Adam Scott (Aus), Michael Thompson, Robert Allenby (Aus), Kyle Reifers, Cameron Beckman, Sang-moon Bae (Kor), Tommy Gainey, D.J. Trahan
76 Chris Kirk, Chris Di Marco, Scott Piercy, Chris Couch, Heath Slocum, Kevin Streelman, Kevin Stadler, Arjun Atwal (Ind), Notah Begay III, Dicky Pride, Y.E. Yang (Kor)
77 Spencer Levin, J J Henry, Ben Crane, John Merrick, Sung Kang (Kor)
78 Bryce Molder, Danny Lee (Nzl), Jeff Maggert, David Mathis, Camilo Villegas (Col), Tom Pernice Jnr.
79 Michael Bradley, Jeff Overton, K J Choi (Kor)
80 Kris Blanks, Lucas Glover
82 Nick O'Hern (Aus)
83 Mark Anderson
