At 23, McIlroy already is a multiple Major winner, but victory at the DP World Tour Championship demanded more of him than those record-shattering efforts at the 2011 US Open and last August's US PGA.
McIlroy had romped home eight strokes clear of the opposition at Congressional and Kiawah, but the world still wondered how 'the kid' would respond with a gun at his head down the stretch.
Well, he provided the answer in a way only a great champion could.
Justin Rose exploded into contention during the final round of this tournament. The Englishman's course record 62 would have had the concussive effect of a hand grenade on most mortals, but it brought out the best in McIlroy.
Suddenly finding himself two behind his Ryder Cup team-mate after a three-putt bogey at the par-three 13th, McIlroy responded in the time-honoured fashion of Sunday matinee idols.
Golf's Holywood star cocked his pump-action shotgun and wreaked a little havoc of his own, finishing with five successive birdies to add the mace of DP World Tour Champion to his massive Race to Dubai trophy.
"Have you ever seen anything like it in your life?" said Michael Bannon, McIlroy's coach from boyhood. "I've never seen a finish like that ... ever! It was just unbelievable. Two behind with five to go and he birdies the next five holes. It was unreal," said Bannon, who this year gave up his job as a Bangor club professional to go on tour with McIlroy.
Like caddie JP Fitzgerald, Bannon's shared in the five victories in 2012 that have propelled McIlroy into a commanding lead at the top of the world rankings and contributed handsomely to the staggering €11,904,126 the youngster has won around the world this year.
"It really has been a fairytale year," Fitzgerald said. "When you're put under the cosh out there – as Rory was – and then do what he did, it's astonishing."
Of the five birdies that brought McIlroy's final round 66 to such a stunning conclusion, Fitzgerald was most impressed by the one he landed on 17.
"That tee shot on 17 was just phenomenal," Fitzgerald said. "We knew what Justin was doing out there, of course we did. To come up with a shot like that when he still needed one birdie in the final two holes really was remarkable."
McIlroy himself rated that 5-iron as his "most important and most pleasing shot," adding: "It was a big shot into a tough pin position.
"You could easily have bailed out right into the bunker, but I committed to it and followed it up with a great putt for birdie to give myself that cushion going up the last," said McIlroy, who eased to 23-under, two strokes clear, with a facile pitch-and-putt birdie four at 18.
"I just wanted to finish the season the way I thought it should be finished," continued McIlroy, who actually wrapped up the Race to Dubai title in Singapore a fortnight back, in the process emulating Luke Donald's historic achievement in 2011 of topping the money list in the US and Europe in the same year.
"You know, I've played so well throughout the year, I just didn't want to let it tail off timidly."
The €1.041m McIlroy earned for his 10th win as a professional and fifth in 115 events on the European Tour boosted his earnings on his home circuit in 2012 to a record €5.5m.
Altogether, he's amassed €26.28m in prize money since turning professional in October 2007.
McIlroy won for the first time on Tour in the 2009 Dubai Desert Classic at the nearby Emirates Club. Yet he's a different player today than the teenager who staggered across the finishing line that February Sunday into the arms of his mum, Rosie, and da, Gerry.
While he has long possessed a wonderful swing and the sort of 'easy power' most of his fellow professionals would die for, McIlroy's developed over recent seasons into a competitor as comfortable as Woods or Nicklaus when the cordite stinks on Sunday – and it's his putting which has developed best.
McIlroy's Danish girlfriend Caroline Wozniacki (22) said: "I think he's matured a lot in the past year or two. He's such a great player – it's amazing to see. He'll keep going for a long time."
Tour officials were delighted when McIlroy and World No 2 Donald played their way into the final group yesterday. In truth, they both took time to get into their stride.
Donald's phenomenal run of 102 holes without a bogey at this tournament came to a conclusion when he three-putted the third and as the round progressed, McIlroy's superior length really began to tell. He seemed to have the title in his pocket until Rose poked his nose in front with an eagle at 14. The highlight of the his round came at 18, which ignited a roar of Augusta proportions with a monster putt which trickled to a halt at the top of the mound before rolling to within a hair's breadth of an eagle. McIlroy stirred Ryder Cup echoes with his five closing birdies, but modestly waved away comparison with his European partner Ian Poulter's stunning conclusion to their Saturday fourballs match at Medinah.
"It's a little different when you need to make five birdies for yourself than when you need to make them for a team – I think that's probably a little more pressure," he said.
Overall, it was a good day for the Irish, Padraig Harrington wrapping up his season with a fabulous 236-yard 5-wood for an eagle at 18, which sealed 68 and earned him €134,972 in a tie for 11th.
Fellow Dubliner Peter Lawrie also closed with an impressive 68 for a share of 14th (worth €109,352).
Though Shane Lowry missed the tournament with a virulent stomach bug, which kept him confined to hospital until yesterday morning, there was good medicine in the shape of a top-29 finish in the Race to Dubai, which seals his place at next July's Open at Muirfield.
When Graeme McDowell sank a 30-foot eagle putt at the last hole for a 69, the €24,995 he won in a share of 52nd place with Michael Hoey placed him ninth in the Race to Dubai Bonus Pool, worth €97,636.
Yet Rory McIlroy fired the shots yesterday that will be heard all around the world. He's as intimidating in red on Sunday as Tiger ever was.