Seamus Power and Padraig Harrington are well placed at the AT&T Byron Nelson at TPC Craig Ranch after bogey-free opening rounds in Texas.
Five birdies paved the way for Power's 65 where the highlight of the day was an eagle on the par-five 18th, chipping in from 30 feet to conclude a memorable round.
The Waterford man sits on seven-under par, two shots adrift of joint leaders JJ Spaun and Jordan Spieth.
Ryder Cup captain Harrington also enjoyed a fine start to the tournament and a round of 66 left the Dubliner on six-under.
The 49-year-old, who began on the back nine, also made hay at the 18th, holing from 48 feet. Harrington hit 18 greens in regulation and added four birdies to the scorecard for a blemish-free round.
Spaun and Spieth are a shot ahead of Rafa Cabrero Bello, Aaron Wise and Doc Redman who are all on eight-under-par.
Spaun birdied three of his first five holes to set up his bogey-free nine-under 63. Spieth also suffered no bogeys, turning at five-under and finishing in grand style by making a 55-foot putt for an eagle three on the 18th.