Hidemichi Tanaka, who played alongside Huston in the final group on Saturday, eagled the par-5 18th to finish two shots back. Tanaka was joined by Paul Stankowski and Chris Anderson in a tie for second at 14-under-par 202. Defending champion Luke Donald was lurking one shot further back at 13-under- par 203.
Huston held a two-shot lead over Tanaka to start the day at Annandale Golf Club and collected two birdies and a bogey over his first five holes. He added a birdie at the seventh to move to 14-under and pulled away from his competitors on the inward half.
The 42-year-old hit his tee shot within five feet of the hole for a birdie at the par-3 12th and followed that up with a birdie at the 13th. At the par-4 14th, Huston landed his approach inside 20 feet and drained the birdie putt to make it three in a row and stretch his lead to four strokes.
Huston, who is in search of his first victory on the PGA Tour since the Tampa Bay Classic in 2000, was coasting down the stretch until a bogey at the 17th shrunk his lead to two shots.
Stankowski tallied three birdies on the front nine and two more on 10 and 12 to reach 13-under. He found trouble with a bogey at the 16th but birdied each of his last two holes for his share of second.
Donald, who earned his first career victory on the PGA Tour at this event last year when bad weather cut the tournament to 54 holes, picked up three birdies over his first nine holes to make the turn at 11-under.
The Englishman added birdies at 11 and 16 before dropping a shot with a bogey at the par-4 17th. Donald recovered with a tap-in birdie at the last to finish three shots off the pace after a round of 67.
South Africa's Tim Clark, who was a captain's pick for this year's Presidents Cup, joined Shigeki Maruyama of Japan in a tie for sixth place at 12-under-par 204.
David Frost, Kent Jones, John E. Morgan and Jim McGovern shared eighth place at 10-under-par 206.
Per-Ulrik Johansson fired a 7-under 65 to finish one shot further back along with Glen Day, Brandt Jobe, Brenden Pappas, Patrick Sheehan, David Peoples and Carlos Franco at 9-under-par 207.
European Ryder Cup captain Bernhard Langer was part of a group at 8-under- par 208 while his American counterpart Hal Sutton was well off the pace at 2-under-par 214.