The Northern Irishman's victory in the Open Championship at Royal Liverpool means that he only needs to win the Masters to become just the sixth player in history to win all four major competitions. The 25-year-old famously took a four-shot lead into the final round at Augusta National in 2011 only to collapse to and finish 10 shots behind the winner Charl Schwartzel.
McIlroy - who is ranked No.2 in the world - enjoyed his only top-10 finish in six appearances at Augusta National earlier this year, but only once he had been out-scored by his non-competing marker in the third round. Rounds of 71 and 77 meant McIlroy made the cut on the mark of four over par and, as the odd man out of the 51 players left in the field, had to play with a marker on Saturday.
Jeff Knox, an Augusta member and two-time former Georgia amateur champion, assumed that enviable role and, beat McIlroy's score of 71 by a single shot. Knox, who holds the course record of 61 from the members' tees, might have enjoyed a greater margin of victory had McIlroy not birdied three of the last four holes. Indeed, in matchplay the Northern Irishman would have lost the tie 4&3.
"Jeff is a great player," said McIlroy at the time. "I thought he was going to be nice and three-putt the last and we would have a half, but he beat me by one. I don't think I've ever seen anyone putt the greens as well as he does around here. I was thinking of maybe getting him to read a few of my putts out there."
McIlroy was able to laugh it off at the time and a closing 69 gave him a share of eighth place. However, he sounded more serious about seeking Knox's help now that a career grand slam will be on the line when he returns to Augusta in April.
"I've always been comfortable from tee to green at Augusta and it's just taken me a few years to figure out the greens and figure out where you need to miss it and some different little shots that you might need that week," said McIlroy, after holding off the challenge of Ryder Cup team-mate Sergio Garcia at Hoylake. "I'll be going into Augusta next year pretty confident . . . if I can just figure out the greens a little bit more. What helped me last year was playing with Jeff Knox in the third round.
"He's the best I've ever seen on Augusta's greens. I might have to take a couple of trips up before it starts next year and have a couple of practice rounds with him."
With a six-shot lead after 54 holes at Royal Liverpool, McIlroy was asked what it would mean for him to lift the Claret Jug. "A lot of hype going into Augusta next year," he said with a smile.
Only Gene Sarazen, Ben Hogan, Gary Player, Jack Nicklaus and Tiger Woods have won all four major titles in their careers, an exclusive club which McIlroy now has the chance to join. Sarazen had to wait longest to win his grand slam - taking 40 events between 1922 to 1935 - but he did have the excuse of the Masters not even existing until 1934. Hogan took 28 events, Player 24, Nicklaus 18 and Woods just 15.
Assuming he plays in next month's US PGA Championship at Valhalla, McIlroy's first attempt to complete the grand slam next April will come in his 25th major appearance as a professional. He was joint 42nd in the 2007 Open as an amateur.
It is all a far cry from 12 months ago when he experienced the lowest point of a largely miserable year by missing the cut at Muirfield, later labelling his play "brain dead" following an opening score of 79. Struggles on the course were not helped by problems off it, McIlroy admitting in November that he had seen enough lawyers to last him a lifetime as a dispute with his former management company headed for the courts.
The former world No.1 got to grips with his new equipment belatedly and secured a first win of the year in December, while he somehow won the BMW PGA Championship at Wentworth in May despite stating on the eve of the tournament that he had called off his wedding to the tennis player Caroline Wozniacki.
"I never had doubts," said McIlroy. "You can't doubt your own ability and all I had to do was look back at some of the great tournaments that I played. The ability was still there. That wasn't it. It was just trying to find a way to make it come out again.
"Missing the cut at Muirfield last year was a very low point. I'd never missed a cut at the Open before and I really missed playing the weekend. I said to myself I'll try to never make that happen again. The win at Wentworth was huge and getting my third major is a huge step in the right direction. There are many more trophies I want to win."