In sport the greatest of dreams can instantly become the stuff of nightmares.

For Rory McIlroy, Thursday's Royal Portrush homecoming for the first round of The Open must have felt like that fabled dream where you're stood naked in front of a room of your peers, as his worst fears were laid bare in front of the world in a torrid round on the Dunluce links.

It simply wasn't supposed to be like this. It wasn't the narrative so many had expected or hoped for, even.

Addressing the media this week, McIlroy discussed how he did not feel like the centre of attention.

It was an admirable attempt at staying low key, but there was never any chance the focus of everyone's attentions at Portrush would not be on the four-time major winner.

Ever since he made a mockery of Portrush's reputation as one of the game's toughest links course as a 16-year-old with a startling course-record 61, McIlroy has been the man in these parts of the world.

But boy did Portrush have its revenge on Thursday and in the cruellest of fashions.

An almighty roar welcomed McIlroy onto the first tee as an expectant home crowd waited with bated breath to see what one of Northern Ireland's greatest sons would produce.

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.

By the time he trudged off the opening green, having made an ugly quadruple eight, the smattering of almost apologetic applause told its own story. 

It was tough viewing as McIlroy scratched his way through the early holes. There was hope a recovery was on the way with birdies at the seventh and the ninth, and he went 12 holes without a bogey.

Yet, just like the showers that arrived at intermittent intervals, that hope proved brief as McIlroy three-putted inside five feet at the 16th – aptly named 'Calamity Corner' – before triple bogeying the last.

A clearly disappointed McIlroy put on a brave face and struck a determined tone, even allowing himself a little joke when asked if there was a way back to the cut mark from 79.

"Definitely a way back to Florida," he quipped. "I definitely think if I can put the ball in the fairway tomorrow I can shoot a good enough score to be around for the weekend. 

"Obviously I'm pretty sure anyone starting with a 79 in this golf tournament doesn't think about winning at this point. But I think I can go out there and shoot something in the mid-60s, be around for the weekend, and then try to play good from there."

Suggestions nerves due to the weight of expectation on his shoulders were a factor were quickly quashed by McIlroy.

"I don't think so. I was nervous on the first tee. But not nervous because of that. Nervous because it's an Open Championship," he added. 

"I usually get nervous on the first tee anyway, regardless of where it is. So maybe a little more so today than other places. But I don't think it was that. It was a bit of a tentative golf swing with a hard wind off to the right and the ball just got going left on me."

There is a sadly familiar pattern in golf's four biggest majors with McIlroy. He has 10 top-10 finishes since he won the last of his four majors at the 2014 US PGA Championship.

But there have not been many times he was genuinely in contention and this week – one of the most important McIlroy has had in his career – is surely now another lost cause.