Defending champion Rory McIlroy faces a battle to make the halfway cut after labouring to a level-par 72 in the first round of the Dubai Duty Free Irish Open.
On a day when 105 of the 156-strong field broke par, tournament host McIlroy could only manage two birdies and two bogeys to end the day eight shots off the lead shared by American Daniel Im and France's Benjamin Hebert.
And playing partners Jon Rahm and Hideki Matsuyama rubbed salt into McIlroy's wounds with rounds of 65 and 67 respectively as the majority of the field took advantage of almost ideal conditions.
"Selflessly it's great to see Jon and Hideki up there, but selfishly I want to be alongside them and it felt like I was going backwards just shooting level par," said McIlroy, who made an early exit from his home event for three years running before his dramatic victory at the K Club in 2016.
"I'm pretty frustrated because it felt like the course was there to shoot a really low score. I could not get anything going and hopefully I can get out there tomorrow morning and make some birdies."
McIlroy, who used three different putters in three rounds on his previous start, had to watch Rahm produce what he described as a "putting clinic", the world number 11 carding six birdies, an eagle and a solitary bogey.
The 22-year-old only turned professional in June last year and is playing just his second regular European Tour event, but said: "To win here would be amazing. Rory's event, the Irish Open... to win this early would be unbelievable."
Flawless rounds of 64 from Im and Hebert established the course record at Portstewart and gave the unlikely duo - with a combined world ranking of 796 - a one-shot lead over Rahm, Oliver Fisher and Matthew Southgate.
Southgate did not have a practice round after qualifying for the Open Championship for the third time in four years on Tuesday, but the 28-year-old from Southend fired seven birdies as he thrived on memories of his fourth place finish last year.
"It completely changed my life," said Southgate, who spent the week of the 2015 Open recovering from an operation for testicular cancer.
"I think the biggest thing for me was that I always thought I was good enough to perform like that, and it was more like proving a point to the rest of the world that I could do it.
"That put me in a nice place mentally because I stopped worrying about, 'Can you do this, what do other people think of you and have you got the game?'.
"It became, 'Actually Matt Southgate is good enough to compete', which is a huge monkey to get off your back."
Fisher recovered from a bogey on the third with seven birdies in his next eight holes and also holed from 30 feet for an eagle on the 13th, but was denied a share of the lead with a bogey on the last.
"I've had some ups and downs and it's certainly a grind at times," said Fisher, who was the youngest player in Walker Cup history when he represented Great Britain and Ireland as a 16-year-old in 2005.
"I know I have it in me, I have the ability, it's just the consistency. The top players are more consistent than those lower down the ladder."
Matt Fitzpatrick, David Drysdale and Jamie Donaldson shared sixth place on six under, with Olympic champion Justin Rose and local favourite Graeme McDowell among those a shot further back.
Donaldson's 66 remarkably included a five-putt double-bogey on the 13th, his fourth hole of the day.
"I hit two really good shots into the par five but I was still asleep," explained Donaldson, who was 25th in the world when he secured the winning point in the 2014 Ryder Cup, but has since slipped to 231st.
"I just casually five-putted, which was kind of bizarre. I just wasn't really paying much attention and thought I was going to be there all day. The last three events I've played pretty good with a top 10, top 15 and 32nd. Just had a lot of injuries over the past 12 months and now they have cleared up."