The 30-year-old four-time major victor is tipped as one of the favourites for the first Open in Northern Ireland since 1951 but already found himself eight shots off the early lead held by Ireland's Shane Lowry.
"I'm going to have days like this, and (I've) got to fight through it". But I feel I'm doing a good job of learning'. One where the Masters champion barely broke 80, the favourite for the tournament fell a spectacular victim to a nation's expectation and the weather matched the ever-changing mood, with players starting holes in sunshine and finishing them with it tipping it down.
McIlroy was tied for 150th on the leaderboard with an 8-over 79 when he finished the first round of the 148th Open Championship, which takes place this weekend at the Dunluce Links course at Royal Portrush Golf Club in County Antrim, Northern Ireland. Then he tried to hit a 230-yard shot into the green with a long iron only to clatter it into a bank and see it go 20 yards. "It was one of those things that I was very proud to be standing on that first tee hitting the first shot".
With early morning sunshine piercing the cloudy skies, Clarke was welcomed on the first tee to huge cheers.
This is the first year since 1972 that The Open is the final major tournament of the season, as the PGA Championship was moved from August to May.
Irishman Shane Lowry and Scotland's Robert MacIntyre were each one shot back, while Sergio Garcia, Alex Noren and Dylan Frittelli - the last man in the field to qualify for The Open after winning the John Deere Classic on Sunday - were at three under par.
No major victor in the past 20 years started a tournament with worse than a double-bogey. He missed a 4-footer for par and then slapped and missed a 1-footer for bogey. "The first tee was definitely a little emotional and a little intimidating", he said, "I was happy to get that away".
A spectator's broken phone as a result of McIlroy's opening wayward tee shot was a fitting metaphor for a round that fell to pieces from the off. He ended up with a triple-bogey 7.
Asked what the difference was for him at Augusta, Woods said, "For some reason, I found something in my golf swing that allowed me to start shaping the golf ball high and draw the ball again".
"And I'm really happy with what I have done this week".
McIlroy came into the tournament as one of favorites, partly because he set the course record at Royal Portrush when he was a 16-year-old amateur.
But instead the 2014 Open champion and victor of three more majors, inarguably Northern Ireland's most successful sporting son, doesn't feel anything but goodwill. "It is one of those God-awful nightmare scenarios which happened today and I happened to be on the end of it".