McIlroy was delighted with his ball-striking during his opening two-under 70 at the County Donegal links, but he was frustrated at missing a number of chances to have been closer – or ahead of – early leader Ryan Fox on five under.
The 29-year-old, who has missed the cut in his home event in four of the last five years, offset a birdie at the long fourth with a mistake at the next before knocking a superb tee-shot in close at the stunning par-three seventh and converting the chance.
After a series of misreads on the greens, McIlroy holed his best putt of the round for birdie at the 12th only to give the shot back at the 15th, but he hit back with a solid birdie at the long 17th to get back to two under par.
Another putt slid past the target from 10 feet at the last which summed up his round, and he aired his frustrations to the media before heading to the practice putting green.
“It could have been a lot better,” said the tournament host. “It’s the best I hit the ball in a long time. I put the ball in play, what I needed to do, and drove the ball very well. My iron play was good as well, but I just struggled on the greens.
“I either hit good putts and just didn’t read them right, or sometimes it was maybe a reaction to putts I had hit previously. It got into my head a little bit. I holed some decent putts, a couple of good ones for par, and that was a nice one on 12 for birdie, but I’m going to need to putt a little bit better over the next three days to have a chance.
“The putt on 18 I felt like I pulled it but some of the other ones I missed left, it was more that I didn’t read them right but I did see the break, it was there. I’m going to go do a bit of work this evening and see if I can straighten it out.
“I’ll sort of figure it out on my own and I don’t think it’s that far away because there’s a lot of putts I felt like I hit good and were just shaving by the edges. I wasn’t missing them by that much. I just need a little bit of confidence, seeing a couple go in early tomorrow, and hopefully it will be a different story.
“I’ve putted well in periods this year, but there have just been times where I haven’t holed that many. But I still feel like I’ve holed my fair share this year, so I just need to try and be a little bit more consistent.”
McIlroy also revealed he did not touch a golf club for a week after finishing tied for 12th at the Travelers Championship, where he was unhappy with too many mistakes in his long game which he blamed on not feeling “comfortable” over the ball at times.
“I didn’t see my golf clubs for seven days, but that helped,” he added. “I picked them back up this week, and I’ve done some really good work with my coach, Michael, over the last three days and felt more comfortable out there.
“I just need to hit more balls on range so I can trust it out there on the course. I trusted everything well out there today. There were a couple of loose shots, but for the most part it was pretty good.”