Seamus Power is 11 shots adrift of the lead after a difficult opening round at the Rocket Classic.
The Waterford native was among just 15 of the 156-player field to shot over par rounds at the Detroit Golf Club with his one-over 73 leaving him in a tie for 142nd.
Power started Thursday's action well with a birdie on the second but a bogey on the fifth set him back. However, it was the ninth that would prove most costly as he double-bogeyed the par-3 hole.
A birdie on 15 offered him solace to lift him up to one over for the day.
Meanwhile at the other end of the leaderboard, Kevin Roy and Aldrich Potgieter share the lead after carding bogey-free rounds of 62.
Both America's Roy and 20-year-old South African Potgieter, who started on the back nine, eagled the 578-yard par-five 17th hole and made eight further birdies to reach 10 under par.
Australia's Min Woo Lee and the United States pair Mark Hubbard and Max Greyserman sit one shot back while Zach Johnson, a former Masters and Open champion, is among a cluster of players on seven under par.
It was a forgettable day for fellow two-time major winner Collin Morikawa, who is seven shots off the pace and bemoaned his short game, including a trio of three-putts on the back nine.
He said in quotes on the PGA Tour's website: "(I) putted like a blind man, honestly.
"It's just an uncomfortable feeling, shoving everything and not being able to square up the face. It's tough."
