Seamus Power is three shots off the lead in a tie for fifth after a bogey-free opening round at the Rocket Mortgage Classic in Detroit.
The Waterford native carded a six-under 66 which leaves him just three shots adrift of leader Davis Thompson.
Power started strongly with a birdie on the 10th, before another on 17.
His positive showing continued on his final nine holes with further birdies on one, seven, eight and nine.
Power sits on six under alongside JJ Spaun, with the pair one shot behind Brandon Hagy, Tom Lewis and Chile's Joaquin Niemann, who are tied for second on seven under, two behind leader Thompson, who carded a bogey-free round with five birdies in his opening nine holes and a further four as he finished with an opening 63.
"If the putter gets hot, you can just kind of ride that wave throughout the day," Thompson, in just his third professional start, said.
"And I was on with my reads today, my caddie did a great job with that. I knew I was hitting it well and I just committed to every target and just stayed in the moment."
Defending champion Bryson DeChambeau shot an even par 72. DeChambeau parted ways with caddie Tim Tucker ahead of the first round. Ben Schomin took over on the bag for DeChambeau and will caddie for him the rest of the tournament.
Watch live coverage of this week's Dubai Duty Free Irish Open on RTÉ2 (Thursday) RTÉ One (Friday-Sunday) and RTÉ Player.