Adam McKendry reports from Augusta
It was billed as McIlroy vs Reed - The Sequel. By the end, McIlroy was no longer even in a starring role. We've seen it before on a Sunday at Augusta, McIlroy in with a tangible shot at the green jacket and then letting it slip from his grasp, albeit this one wasn't anywhere near as bad as 2011.
American Reed went on to win The Masters by one shot from compatriot Rickie Fowler.
Starting three shots behind Reed at the start of the day's play, the Holywood man was back within a stroke by the time the pair walked off the second, but that was to be as good as it got for him.
In fact, that second should have been better, his utterly sublime approach to the par-five leaving him a four-footer for eagle. McIlroy hadn't missed from inside five feet all week. When faced with the chance to tie the lead, he couldn't sink it.
After that, things didn't improve, to the extent that, by the time the final pairing had made the turn, Reed's nearest competitor was now Jordan Spieth who was tearing the course up three holes ahead.
Instead, what unfolded was one of the most thrilling ends to a Masters tournament in recent memory as several of the world's best players rapidly tracked down Reed, who was ambling along at level par.
But the former Augusta State man held on, a crucial birdie at the 14th, coupled with Spieth's problems on the closing hole, setting him on his way to his first Major victory and the Green Jacket.
Reed finished on 15 under, one shot ahead of Fowler who carded a five under round of 67.
When it was all said and done, McIlroy had finished in a tie for fifth alongside Cameron Smith, Bubba Watson and Henrik Stenson.
His wait for the Grand Slam will extend until at least next April when he returns with another frustrating Augusta memory driving him on, and this one will sting just as much as any other.
Perhaps it was the relentless persistence of the local media driving this up as a rematch of that exhilarating Ryder Cup match at Hazeltine, or maybe it was just the pressure of that Grand Slam chance that got to him.
Whatever it was, McIlroy's first shot set the tone for the day, a wild flail with the driver that sent the ball careering way right of the fairway.
A wince from the World No.7 and a quizzical look to caddy Harry Diamond. Despite making par, and the birdie at the second getting the crowd on their feet, consistency was the issue.
He gave a shot back at the third, regained it at the fourth after another excellent approach but then contrived to bogey the par five eighth.
The charge was killed at the ninth, another thumping drive leaving him a wedge in that rolled to nine feet, but the putt didn't even shave the hole on the way by.
The gap between him and Reed was four, and looked unassailable.
A bogey followed at 11 and, although he got it back at the 13th, it was too little too late.
From there, McIlroy's round petered out substantially. He missed a two-footer on 14 for par and couldn't find a birdie to close out his round at least on some sort of a high.
Where did it go wrong? Perhaps a better question would be where it didn't go right.
The driving, a problem on Friday and Saturday too, was erratic and his excellent putting, which had surprisingly been his saviour over the opening three days, took flight and headed south.
Coming into the round he hadn't missed a putt inside five feet.
By the 11th he'd missed three.
His longest putt of the day came on the first from all of six feet to rescue par, but in truth he wasn't getting enough good looks at birdie to get the putter firing again.
It's not anything close to a crisis yet - McIlroy will be back and he will get more chances to don the Green Jacket.
He loves Augusta, Augusta loves him and his game is good enough and suited to the Georgian gem.
However, you look at Phil Mickelson, who still awaits that elusive US Open. He's a legend of the game, but ask him if he's happy with just the three Majors and I'm willing to bet he wouldn't give you a positive answer.
McIlroy has more time on his side, but the sooner he does it, the better.
This was a chance to end the hoodoo and ensure he will go down in golfing history. Instead, he'll have to try his luck again next year.
He will be back, don't doubt it.
But for now, the wait goes on.
Paul Casey, meanwhile, savoured a memorable weekend at the Masters despite missing out on a share of the course record at Augusta National.
Casey was on course to equal the record of 63 shared by Greg Norman and Nick Price, or even match the major championship mark of 62 held by Branden Grace, when he covered his first 15 holes in nine under.
After going to the turn in 33, Casey birdied the 11th and 12th, eagled the 13th and also birdied the 14th and 15th, but the 40-year-old was unable to save par from a greenside bunker on the 17th and three-putted the last for a 65.
"That was fun, wasn't it?" Casey said. "Birdie, birdie, eagle on Amen Corner, I'm going to remember that for a long time.
"I'm obviously disappointed (with the finish). I got out of position horribly on 17 and 18 which was kind of reminiscent of how I played this week. Haven't been very good until that streak today.
"But to shoot 65 today, it would have been hard to turn that down.
"I know 63 is the course record, 62 is the lowest ever in a major.
"So I was aware. Not particularly nervous, just kind of having a good time and obviously didn't do it, but it was fun."