Defending champion Jonas Blixt leads the Greenbrier Classic by a single stroke at the end of a low-scoring first day at White Sulphur Springs.
The Swede mixed eight birdies with two bogeys to sign for a six-under 64 while seven Americans - including Chris Kirk and DA Points - and New Zealand's Danny Lee are all one shot back on five under.
Darren Clarke is seven strokes off the pace after a first round of 71.
Blixt, 30, shot his first round in the 60s in his last 18 attempts while making his way around the West Virginia course in what he described as "fantastic conditions".
He struck his 175-yard approach shot to within three feet of the sixth hole before putting for the birdie and almost holed out from 49 feet on the par-three eighth, jarring the flagstick as he settled for par.
Speaking to pgatour.com, Blixt said: "I got off to a good start and got some good breaks in the morning and it's always nice to go out there and produce again after winning a golf tournament.
"There was low wind - fantastic conditions in which to score low. Me and my caddie talked about it and we just fired everything today. We did that and it kind of worked out."
Referring to his classy up-and-downs on the seventh and eighth holes, he added: "Instead of hitting fade I just hit a little draw and the wind took it and it went over the green and I had a good lie.
"It depends on the ridges sometimes and it went away a little further than I thought but I'm happy to make those shots coming back and it keeps the run going to keep you in the tournament."
While Points, James Hahn, Jason Bohn, Joe Durant, Patrick Rodgers, Jim Renner and Rotorua's Lee are chasing Blixt hard after carding 65s on Thursday, only one man from the large group tied for second place returned to the clubhouse without signing for a bogey.
Atlanta-born Kirk found birdies on the third, eighth, 10th, 11th and 16th holes to prolong his bright run of form on the PGA Tour.
The 29-year-old said: "The greens are just perfect, so that's why you're seeing the good scores."
Among those tied for third place on four under are Sang-Moon Bae of South Korea, Steve Stricker and Kevin Na.
Masters champion Bubba Watson had a less productive day, signing for a two-under 68 that saw the effect of five birdies sullied by three bogeys.
England's Brian Davis is down in a share of 54th place after a one-under 69 and Northern Irishman Darren Clarke is one over for the tournament having tempered two bogeys with a single birdie.
Elsewhere in the field, Louisiana's Andrew Loupe came within one foot of recording an albatross on the par-five 17th after striking his 279-yard approach shot to within easy putting distance of the hole.