Washington - American Chris Kirk, seeking his fifth PGA title, fired a bogey-free nine-under-par 63 to grab a one-stroke lead after Thursday's opening round of the RSM Classic.
Kirk, whose most recent triumph came 2 1/2 years ago at Colonial, eagled the par-5 18th at the Plantation course in Sea Island, Georgia, to overtake compatriot Joel Dahmen.
The PGA Tour's final 2017 event is played over the par-70 Seaside course and par-72 Plantation layout for the first two rounds. The last two rounds are played on the Seaside course.
Kirk, whose best major finish was a share of 19th at the 2014 British Open, opened with a birdie, added another at the par-5 fourth and ran off three birdies in a row, a streak ending after he birdied the par-5 eighth. He birdied 14 and the par-5 16th before his closing eagle.
Other PGA wins for Kirk came at the 2011 Viking Classic, the 2013 McGladrey Classic and the 2014 Deutsche Bank Championship.
Dahmen birdied three of the first six holes and then three in a row, a run ending at the par-4 10th. He closed the round with birdies at 17 and 18 for a 64.
Americans Jason Kokrak, Hudson Swafford and Brian Gay shot 65 to share third with South Korean Kang Sung and American Austin Cook on 66.
Nick Watney and Brice Garnett had the low scores on the Seaside course in round one with 65s to stand on five-under alongside eight players who shot 67 at Plantation, a pack that included Zimbabwe's Brendon de Jonge, Scotland's Russell Knox and Canada's Ben Silverman.
Leading scores after Thursday's opening round of the US PGA RSM Classic on the par-70 Seaside and par-72 Plantation courses at Sea Island, Georgia (USA unless noted):
63 - Chris Kirk
64 - Joel Dahmen
65 - Jason Kokrak, Hudson Swafford, Brian Gay
66 - Austin Cook, Kang Sung (KOR)
67 - Blayne Barber, Richy Werenski, Vaughn Taylor, Webb Simpson, Keith Mitchell, Brendon de Jonge (ZIM), Russell Knox (SCO), Ben Silverman (CAN)
65 - Nick Watney, Brice Garnett
68 - Nick Taylor (CAN), Tyrone Van Aswegan (RSA), Tyler Duncan, Michael Thompson, Ken Duke, Troy Merritt, Aaron Wise
66 - Michael Kim, Brandon Harkins, Patton Kizzire