Amateur James Sugrue carded a terrific three-under-par 67 to lead the home charge at the Dubai Duty Free Irish Open, but Shane Lowry racked up eight bogeys in a hugely frustrating five-over 75 that seriously dented his ambitions.
Lowry - playing on Irish soil for the first time since winning the 2019 British Open at Royal Portrush - bogeyed three of his first six holes and never recovered.
Lowry had high hopes of making a charge at the title he won as an amateur back in 2009, flying straight from last week's US Open to play.
However, he now faces a major battle just to make the weekend.
"It was a comedy of errors out there," he told RTÉ Sport afterwards.
"I executed my shots really badly and I shot really badly on the greens. I really wanted to do well but it is what it is. I can't do anything about it now. I just have to go out tomorrow and fight to make the cut."
Sugrue on the other hand will be over the moon with his first round at Galgorm Castle.
The 24-year-old is one of three Irish amateurs in the field - Mark Power (+4) and Tom McKibbin (+3) are the others - and he showed no hint of nerves in a highly assured start.
Speaking to RTÉ Sport, Sugrue said: "It's hard to know where the wind is blowing out there. It can swirl around with those big trees all around you.
"I think I only hit two poor drives, which was at the first and the last. I was pleased with how I hit it off the tee."
South African Dean Burmester set the early pace with a five-under 65 that was blemished by a double bogey on the last. That score leads the way heading into Friday, with English duo of Jordan Smith and Aaron Rai also on that mark.
Damien McGrane, Jonathan Caldwell and Padraig Harrington all carded 71s to stand at +1.
Indeed Harrington's knowledge of golf rules saw him take action to move a large branch after his ball went well wide of the fairway. In finding his ball, the Dubliner swing was impeded by the branch. Under Rule 15.1, the obstacle was considered a loose impediment and so could be moved.
Early starter Burmester raced to seven under after 12 holes as thoughts harboured of the second 59 in European Tour history at Galgorm Castle.
Four pars followed to derail those thoughts before the South African double-bogeyed the penultimate hole to drop to five under par, although this still proved to be a daunting clubhouse target.
Smith and Rai were the only players to go blemish-free as they carded five birdies to match Burmester at the top of the leaderboard.
Smith picked up shots at the second and eighth before adding further gains at the 10th and 12th to sit one adrift. And when the 27-year-old rolled in his fifth birdie at the 16th, he was the joint leader.
Rai recorded just one birdie on the front nine - at the sixth - before dialling in on the back nine.
He picked up shots at the 10th, 12th, 14th and 16th but could not improve his score as he made it a three-way tie.
Toby Tree mixed an eagle, four birdies and two bogeys to sit in solo fourth place at four under.