Fourteen months after winning the US Open by a massive eight shots, the 23-year-old Northern Irishman astonishingly did the same in the USPGA Championship at Kiawah Island last night.
McIlroy's first major title had come with a record score and his second was by a record margin in the event, beating the seven strokes of Jack Nicklaus in 1970.
More than that, the Holywood golfer - now starting his fourth reign as world number one and intent on making it a longer one than the first three - had become a multiple major winner at a younger age than Nicklaus, Tiger Woods and all but four players in golf history.
Those four were Young Tom Morris in the 1860s, John McDermott and Gene Sarazen just before and after the First World War and Seve Ballesteros.
As satisfying as all that is, McIlroy took extra pleasure in winning so emphatically so soon after questions were being asked about where his career was heading - not surprisingly given he missed four halfway cuts in five starts.
"A few people in this room were probably pressing panic buttons for no reason," the biggest young talent in the game told a crowded press conference.
"I don't think I could have answered it in any better way - and yeah, to be honest, it did motivate me.
"I did want to go out there and prove a few people wrong.
"That's what I did. It took me all of four weeks to get my game back in shape and get out of my mini slump - and this is the result.
"To sit up here and see this trophy and call myself a multiple major champion... not many people have done it and I'm very privileged to join such an elite list of names."
McIlroy, who left the rest for dead in the first golf tournament to have 99 of the world's top 100 playing in it, smiled when reminded he had just taken a record off Nicklaus.
"I don't care if I win by one or by eight - I just want to win - but it's nice to break a record like that, especially of Jack Nicklaus," he said.
"He's the most successful player of all time so far. It's a nice achievement."
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The US Open last year saw McIlroy take the lead on the first day and gradually move away, but this was different.
He was three clear with a round to go, but that became only one when Ian Poulter leapt out of the pack by starting with five birdies in a row and six in seven holes.
McIlroy knew about it and put his foot on the accelerator. He turned in 33 to Poulter's 31 and while his Ryder Cup team-mate faltered he added further birdies at the 12th, 16th and 18th.
Poulter's slip allowed compatriot David Lynn to be the surprise runner-up. This was the 38-year-old first major in America and only the second of a career in which he was won just one of 371 European Tour events.
He qualified by being in the world's top 100 and now is 40th - and he is exempt for next April's Masters now.
Poulter, runner-up to Padraig Harrington in the 2008 Open, shared third with another Englishman, Justin Rose, defending champion Keegan Bradley and Swede Carl Pettersson. Woods was joint 11th.