Rory McIlroy’s frustration at letting the WGC-Cadillac Championship slip away was a timely reminder of how difficult it will be to complete the career Grand Slam at the Masters.

Armchair critics will say that the new world No 2 — the silver lining is that he leapfrogged Jason Day in the latest world rankings — was too defensive and allowed his rivals to streak past him on the final day.

But winner Adam Scott, who echoed Padraig Harrington’s belief that there is probably a Big Six or Seven and not a Big Three, was the first to defend the Holywood star.

“It’s hard work to become relevant with you guys,” the Aussie joked after his news conference. “Guys are playing so consistently. I have to win back to back to become relevant with you guys. That’s what it takes. 

"If it is not me, it’s Bubba getting his second win in a row. And today Rory is leading a tournament again, and you have Rickie Fowler and Jordan Spieth and the list goes on and on.” 

Like McIlroy, Scott knows what it’s like to turn what’s billed as a triumphal procession in a major into a shattering loss. The 2012 Open championship, presented on a plate to Ernie Els, ranks up there with McIlroy’s 2011 Masters loss as one of the most painful Sunday afternoon unravellings you are likely to see.

The WGC-Cadillac Championship at Donald Trump’s Blue Monster is not a major but given the field and the golf course, it’s only one step removed.

Sunday’s win by Scott is a reminder, not just that the Australian can win a second green jacket with a conventional putter following two hugely impressive wins in a row, but that Bubba Watson is probably the man to beat at Augusta. And don’t forget about Phil Mickelson and Danny Willett and the rest.

“Even if I won every tournament I play before the Masters, if Bubba keeps finishing second, I’d still think he's favourite,” Scott said of Watson. “You know, I'm happy if my name is in the mix. I wouldn't shy away from it. I’m not just trying to put the pressure on Bubba, but he's obviously playing fantastic. 

"He won L.A. and second here, and Augusta around the corner, he's got to be thinking this is looking really good for him.”

McIlroy didn’t hang around for Watson to finish speaking on a dais near the scorer’s hut so that he could be interrogated about losing what was at one stage a four-shot lead.

He spoke on the march about not making enough birdies and how frustrating it has been not to convert final day leads in Los Angeles and Miami into wins.

Add to that his missed cut in the Honda and it would be tempting to think McIlroy has a real problem. He doesn’t.

His new putting grip has had the hoped for effect and given him confidence on the greens but his long game was slightly off on Sunday and that led to pressure.

Without having seen any of the play, Scott wasn’t surprised McIlroy didn’t shoot another 68 to win by four.

“I will say it in the right way  - I am not surprised,” he said. “It is so hard out there. I don’t know how he played.” 

Told McIlroy didn’t have a birdie putt inside 30 feet until the 12th, he added: “Yes, it is very hard to force it in there close because the penalty is water. I made two doubles and as the leader, that’s certainly not what you want to do. 

“He probably didn’t make the putts he would have liked today and did’t quite have it. It is hard going out there with the lead, it really is. It’s harder than ever. 

“A three-shot lead on a tough course like this is not a lot. It’s a birdie to a double. It’s one good shot to a bad shot. That’s literally how fine a line it is. If I hit a good shot and he hits a bad shot on that hole there’s three shots gone.”

At the age of 35, it would be tempting to say that Scott’s experience was key against a four-time major winner. 

But he admitted that he has only learned in recent years how to read a major event, how to be patient and how to attack, even if his final round was an anomaly for the brace of early double bogeys and the rash of birdies in that homeward nine of 32.

“I think one thing I have going for me over the young stars of the game is some experience, and maybe that played a little part in my thinking today,” he said. 

“But you know, again, yeah, to have that kind of thought like it's still tough and I didn't need to birdie five in a row to get it straight back. 

“That comes from understanding how World Golf Championships, majors, Players Championships work, and even Honda Classics on tough golf courses. It's hard to just run away with it.

“If Rory went out and shot 67 or 68 today, that's phenomenal. You can't compete against that. But it wasn't easy for him to do that, even playing as good as he is.”

“Not to say that I have more experience than Rory, because he's won four majors and played in this position a lot in his 26 years already.

“And when I was that age, or ten years ago, I had not, and I didn't know how to think or to think it's a hard course, everyone's going to have their struggles today. 

“I probably thought, oh, it had to be so perfect and if it wasn't, you didn't have a chance and I didn't manage my mind or my game well at that point.

“You know, I kind of went against my own theory this week because I try and avoid doubles, and worse, because they are very costly. And somehow, I think because I was playing so well, I got away with it… I guess I just know how to play tougher golf courses in the bigger tournaments better than ten years ago.”

As McIlroy was hitting the ball to 30 feet, Scott hit four shots inside four feet on the back nine.

"By the time I had made the turn, I had made a couple birdies, and Rory had dropped a shot and I thought with a great back nine I was in with a chance, and what's that I tried to do.

"And then all of a sudden, I just started getting nice numbers into the greens, and I kind of hit my way to win this tournament. I hit it close three times on the back nine and four times, I hit a three-wood on the green and 2-putted on 10 and then hit it to four feet or less, three other times, and that's kind of how it all happened. Took a lot of pressure off on some hard holes."