Denmark and the United States represented the first-round lead at the US PGA Championship as Thorbjorn Olesen and Kevin Kisner shot matching four-under-par 67s on Thursday.
Playing early in the morning, Olesen carded six birdies and two bogeys to post an early lead and outshine world number one Dustin Johnson, Jordan Spieth, Jason Day and Rory McIlroy at Quail Hollow.
Kisner, born in South Carolina, joined him at four under in the afternoon with a birdie on his final hole in Charlotte.
Olesen finished tied for 10th at last week's WGC-Bridgestone after firing a 5-under 65 in the final round.
He carried over that momentum on Thursday to become the unlikely first-round co-leader in North Carolina.
Having already won his first major at this year's U.S. Open, Brooks Koepka put himself back in contention this week with an opening 68.
Grayson Murray, Gary Woodland, Chris Stroud and D.A. Points joined Koepka at three under.
Rickie Fowler led a group at two under after firing a 69 with six birdies, a bogey and a messy triple-bogey on the par-four fifth hole.
Fowler was already two under through four holes when he caught the lip of the fairway bunker on his second shot on the fifth, and the hole snowballed from there.
Bud Cauley joined Fowler in the clubhouse with a two-under 69.
Cauley has two top-five finishes this season, but he is still searching for his first-career PGA Tour win.
Paul Casey, Patrick Reed, Jim Herman, Brian Harman and Tony Finau also closed the day two shots off the pace.
Day, Johnson and Hideki Matsuyama all shot one-under 70s to remain within touching distance of the lead.
Johnson was the most steady of the three, finishing his round with three birdies and two bogeys.
Golf's top-ranked player had no trouble manoeuvring his way around the course, but he was not able to get much going on the greens.
Day, who played alongside Johnson in round one, had two birdies and an eagle in his last five holes to get back into red figures. He played his first 12 holes in three-over par, but quickly rediscovered his form.
With the added pressure of possibly becoming the youngest to ever win a career Grand Slam, Spieth opened with a 72.
Spieth birdied two of his last three holes to give himself a good chance to rebound during the next three days.
McIlroy, who made it to two under at one point, also finished his day at one over.
A double-bogey at the short par-four 14th, on the heels of a bogey on 13, ended all his momentum.
Phil Mickelson and defending champion Jimmy Walker played together on Thursday, and they hit way more shots than they intended at the start of the day.
Mickelson shot an eight-over 79 with no birdies on the card, while Walker posted an ugly 10-over 81.