England's Paul Casey and Thailand's Kiradech Aphibarnrat both made impressive starts at the US PGA Championship as the early starters looked to take advantage of a rain-softened Oak Hill.
Overnight rain had cleared in time to leave ideal scoring conditions Casey and Aphibarnrat, as well as World Number One Tiger Woods, reached the turn in two under par to lie two behind early pacesetters Robert Garrigus and David Hearn.
Casey, a 12-time European Tour winner, turned in a one over par 36 after starting at the tenth and bogeying his opening hole.
But he started for home with four birdies in five holes - only a dropped shot at the third spoiling his run - to be two under with three to play.
Maybank Malaysian Open winner Aphibarnrat was on the same mark after birdieing the ninth, tenth and 13th, with his only bogey coming at the 12th.
Fresh from winning his eighth WGC Bridgestone Invitational on Sunday by seven shots, Woods started on the back nine and holed from eight feet for par on the tenth after charging a long-range birdie attempt past the hole.
The 37 year old, who has gone 17 Majors without a win since the 2008 US Open Championship, then missed the green on the par three 11th but chipped to within three feet of the flag to save par.
A creek which runs across the 13th fairway around 300 yards from the tee meant Woods hit an iron off the tee, despite the par five measuring 598 yards, but after another iron left him 150 yards from the green he fired a superb approach to within two feet of the flag to set up his first birdie of the day.
Woods also birdied the par three 15th, holing from ten feet, and saved par from a greenside bunker on the 18th to be out in 33.
Garrigus was in the second group out at 7:25am and birdied the 11th, 12th and 13th before a bogey on the 18th, but hit back with further birdies on the second and fourth.
He was joined on four under by Canada's Hearn, who had bogeyed the first hole but hit back with birdies at the second, fourth and sixth to be out in 33 before picking up further shots on the tenth and 11th.
Woods had an excellent chance for another birdie on the second after an excellent approach, but his putt from three feet never even touched the hole.
Casey made no such mistake on the seventh, the former Ryder Cup star's fifth birdie in seven holes taking him to three under and just one behind Hearn and former US Open Champion Jim Furyk.
